Replace remaning references to ribbon to TabbedCommandBar (#3890)

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## Some references to ribbon removed
<!-- Add the relevant issue number after the "#" mentioned above (for ex: Fixes #1234) which will automatically close the issue once the PR is merged. -->

<!-- Add a brief overview here of the feature/bug & fix. -->
Replaces certain referecnes to ribbon with TabbedCommandBar

## PR Type
What kind of change does this PR introduce?
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- Bugfix
<!-- - Feature -->
<!-- - Code style update (formatting) -->
<!-- - Refactoring (no functional changes, no api changes) -->
<!-- - Build or CI related changes -->
<!-- - Documentation content changes -->
<!-- - Sample app changes -->
<!-- - Other... Please describe: -->


## What is the current behavior?
<!-- Please describe the current behavior that you are modifying, or link to a relevant issue. -->


## What is the new behavior?
<!-- Describe how was this issue resolved or changed? -->


## PR Checklist

Please check if your PR fulfills the following requirements:

- [ ] Tested code with current [supported SDKs](../readme.md#supported)
- [ ] Pull Request has been submitted to the documentation repository [instructions](..\contributing.md#docs). Link: <!-- docs PR link -->
- [ ] Sample in sample app has been added / updated (for bug fixes / features)
    - [ ] Icon has been created (if new sample) following the [Thumbnail Style Guide and templates](https://github.com/windows-toolkit/WindowsCommunityToolkit-design-assets)
- [ ] New major technical changes in the toolkit have or will be added to the [Wiki](https://github.com/windows-toolkit/WindowsCommunityToolkit/wiki) e.g. build changes, source generators, testing infrastructure, sample creation changes, etc...
- [ ] Tests for the changes have been added (for bug fixes / features) (if applicable)
- [ ] Header has been added to all new source files (run *build/UpdateHeaders.bat*)
- [ ] Contains **NO** breaking changes

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## Other information

.github/ISSUE_TEMPLATE/feature_request.md

@@ -15,7 +15,7 @@ IF NOT CERTAIN ABOUT THE FEATURE AND REQUIRE MORE CLARITY THEN PLEASE POST ON "I
 <!-- Please describe or link to any existing issues or discussions.
 A clear and concise description of what the problem is, starting with the user story. 
 Provide examples of the restrictions in the current environment that hinders the work your users or you want to perform. What are the ways this new feature will help transform and deliver those results?
-For example, I am currently using the InfiniteCanvas control which lacks the ribbon control feature. I am looking to improve user experience therefore i would like to use that in my project to provide ease of accessibility and a user-friendly interface. This new feature will provide quick access to the toolbar, enhance space utilization, etc [...] -->
+For example, I am currently using the InfiniteCanvas control which lacks the TabbedCommandBar control feature. I am looking to improve user experience therefore i would like to use that in my project to provide ease of accessibility and a user-friendly interface. This new feature will provide quick access to the toolbar, enhance space utilization, etc [...] -->
 
 
 ## Describe the solution

Microsoft.Toolkit.Uwp.UI.Controls.Core/TabbedCommandBar/TabbedCommandBar.cs

@@ -12,16 +12,16 @@
 namespace Microsoft.Toolkit.Uwp.UI.Controls
 {
     /// <summary>
-    /// A basic ribbon control that houses <see cref="TabbedCommandBarItem"/>s
+    /// A basic TabbedCommandBar control that houses <see cref="TabbedCommandBarItem"/>s
     /// </summary>
     [ContentProperty(Name = nameof(MenuItems))]
-    [TemplatePart(Name = "PART_RibbonContent", Type = typeof(ContentControl))]
-    [TemplatePart(Name = "PART_RibbonContentBorder", Type = typeof(Border))]
+    [TemplatePart(Name = "PART_TabbedCommandBarContent", Type = typeof(ContentControl))]
+    [TemplatePart(Name = "PART_TabbedCommandBarContentBorder", Type = typeof(Border))]
     [TemplatePart(Name = "PART_TabChangedStoryboard", Type = typeof(Storyboard))]
     public class TabbedCommandBar : NavigationView
     {
-        private ContentControl _ribbonContent = null;
-        private Border _ribbonContentBorder = null;
+        private ContentControl _tabbedCommandBarContent = null;
+        private Border _tabbedCommandBarContentBorder = null;
         private Storyboard _tabChangedStoryboard = null;
 
         /// <summary>
@@ -45,14 +45,14 @@ protected override void OnApplyTemplate()
         {
             base.OnApplyTemplate();
 
-            if (_ribbonContent != null)
+            if (_tabbedCommandBarContent != null)
             {
-                _ribbonContent.Content = null;
+                _tabbedCommandBarContent.Content = null;
             }
 
-            // Get RibbonContent first, since setting SelectedItem requires it
-            _ribbonContent = GetTemplateChild("PART_RibbonContent") as ContentControl;
-            _ribbonContentBorder = GetTemplateChild("PART_RibbonContentBorder") as Border;
+            // Get TabbedCommandBarContent first, since setting SelectedItem requires it
+            _tabbedCommandBarContent = GetTemplateChild("PART_TabbedCommandBarContent") as ContentControl;
+            _tabbedCommandBarContentBorder = GetTemplateChild("PART_TabbedCommandBarContentBorder") as Border;
             _tabChangedStoryboard = GetTemplateChild("TabChangedStoryboard") as Storyboard;
 
             SelectedItem = MenuItems.FirstOrDefault();
@@ -83,7 +83,7 @@ private void SelectedItemChanged(NavigationView sender, NavigationViewSelectionC
             _visibilityChangedToken =
             _previousSelectedItem.RegisterPropertyChangedCallback(TabbedCommandBarItem.VisibilityProperty, SelectedItemVisibilityChanged);
 
-            // Set the ribbon background and start the transition animation
+            // Set the TabbedCommandBar background and start the transition animation
             _tabChangedStoryboard?.Begin();
         }
 

Microsoft.Toolkit.Uwp.UI.Controls.Core/TabbedCommandBar/TabbedCommandBar.xaml

@@ -250,17 +250,17 @@
                         </Grid>
 
 
-                        <Border x:Name="PART_RibbonContentBorder"
+                        <Border x:Name="PART_TabbedCommandBarContentBorder"
                                 Grid.Row="1"
                                 HorizontalAlignment="Stretch"
                                 VerticalAlignment="Stretch"
-                                Background="{Binding ElementName=PART_RibbonContent, Path=Content.Background}">
-                            <ContentControl x:Name="PART_RibbonContent"
+                                Background="{Binding ElementName=PART_TabbedCommandBarContent, Path=Content.Background}">
+                            <ContentControl x:Name="PART_TabbedCommandBarContent"
                                             HorizontalContentAlignment="Stretch"
                                             Content="{TemplateBinding SelectedItem}">
                                 <ContentControl.Resources>
                                     <Storyboard x:Name="TabChangedStoryboard">
-                                        <PopInThemeAnimation TargetName="PART_RibbonContent" />
+                                        <PopInThemeAnimation TargetName="PART_TabbedCommandBarContent" />
                                     </Storyboard>
 
                                     <!--

Microsoft.Toolkit.Uwp.UI.Controls.Core/TabbedCommandBar/TabbedCommandBarItem.cs

@@ -35,7 +35,7 @@ public TabbedCommandBarItem()
             new PropertyMetadata(string.Empty));
 
         /// <summary>
-        /// Gets or sets the text or <see cref="UIElement"/> to display in the header of this ribbon tab.
+        /// Gets or sets the text or <see cref="UIElement"/> to display in the header of this TabbedCommandBar tab.
         /// </summary>
         public object Header
         {