Feature: Added support for customizing the toolbar

[yair100]

Resolved / Related Issues

To prevent extra work, all changes to the Files codebase must link to an approved issue marked as Ready to build. Please insert the issue number following the hashtag with the issue number that this Pull Request resolves.

• Closes Feature: Allow adding actions to the toolbar #16188
• Closes Feature: Add Labels to the Actions Icons Toolbar #17350

Code Changes

• Added an ExtendedLabel property to actions. This property inherits the Label content by default but can be overridden when necessary. An example of where this is used is for the group & sort options. These commands sometimes have similar labels which is okay when they are displayed in a menu flyout, but additional context is needed when they are displayed in settings.
• Added an ActionCategory property to actions. This category is used to group available actions in the customization window. This PR also adds a converter to convert the category enum to a localized string.
• Added AccessKeys and AutomationIds to the action files (these were previously hardcoded in xaml).

The changes have been tested extensively, but it needs a careful code review since it's mainly AI generated.

Steps used to test these changes

Stability is a top priority for Files and all changes are required to go through testing before being merged into the repo. Please include a list of steps that you used to test this PR.

1. Opened Files ...
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