fix(many): form controls labels have increased margin (#27447)

Issue number: resolves #27129

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issue. -->

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

Material Design has 16px of margin between the form control and the
label, but we have 8px:
https://m2.material.io/components/selection-controls#usage

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- Updates default margin from 8px to 16px for checkbox, input, radio,
range, select, textarea, and toggle.

Note: This should only apply to labels that are on the same line as the
form control. In other words, they do not apply to stacked/floating
labels.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

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screenshots of how the component looks before and after the change. -->

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Co-authored-by: ionitron <hi@ionicframework.com>

Author: liamdebeasi

core/src/components/checkbox/checkbox.scss

@@ -194,7 +194,7 @@ input {
    * the checkbox should be on the end
    * when the label sits at the start.
    */
-  @include margin(0, 8px, 0, 0);
+  @include margin(0, $form-control-label-margin, 0, 0);
 }
 
 
@@ -215,7 +215,7 @@ input {
  * when the label sits at the end.
  */
 :host(.checkbox-label-placement-end) .label-text-wrapper {
-  @include margin(0, 0, 0, 8px);
+  @include margin(0, 0, 0, $form-control-label-margin);
 }
 
 
@@ -228,7 +228,7 @@ input {
    * the checkbox should be on the end
    * when the label sits at the start.
    */
-  @include margin(0, 8px, 0, 0);
+  @include margin(0, $form-control-label-margin, 0, 0);
 }
 
 /**