Make Close buttons consistent

[krschau]

Summary of the pull request

We use a Close button ("X" button") in a few places in Dev Home. This change creates a CloseButton control so that styling (Margin, Padding, Alignment, Text) will be consistent throughout. Also remove FontIconSource and FontIconClose from SetupToolStyles.xaml, which are not used anywhere.

References and relevant issues

#916

Detailed description of the pull request / Additional comments

Validation steps performed

PR checklist

• Closes Ensure dialog "exit" buttons are consistently styled #916
• Tests added/passed
• Documentation updated

[guimafelipe]

We will need to add a localized AutomationProperties.Name to this control later, as the narrator will read it as "Button" and nothing else.

[dhoehna]

Can the common close button view be used in the setuptool project? That has a close button.

[krschau]

Can the common close button view be used in the setuptool project? That has a close button.

@dhoehna Can you point me to where you're talking about? Searching I see there's two other places where glyph E711 are referenced, but since they're in their own control, I wasn't sure I should mess with them.

                            <ctControls:SettingsCard.ActionIcon>
                                <FontIcon FontFamily="{ThemeResource SymbolThemeFontFamily}" Glyph="&#xE711;"/>
                            </ctControls:SettingsCard.ActionIcon>

[dhoehna]

https://github.com/microsoft/devhome/blob/main/tools/SetupFlow/DevHome.SetupFlow/Views/SummaryView.xaml#L66

I use the symbolIcon.

[krschau]

@dhoehna I updated SummaryView to use it. I tried it out myself and it looked good, but you may want to double check it. (The Padding is a little bigger in my control, but only by 5 pixels)