fix: primarycommand text theme changing

[rajamatt]

GitHub Issue (If applicable): closes #1341

PR Type

What kind of change does this PR introduce?

• Bugfix

The following code was tested:

<utu:NavigationBar.PrimaryCommands>
	<AppBarButton Label="More" Style="{StaticResource DefaultAppBarButtonStyle}" />
	<AppBarButton Content="More" Style="{StaticResource DefaultAppBarButtonStyle}" />
</utu:NavigationBar.PrimaryCommands>

What is the current behavior?

See linked issue for video. PrimaryCommands weren't being invalidated when they only contained text (label or content).

What is the new behavior?

Setting the ActionView that the PrimaryCommand displays allows them to be invalidated on a theme change.

Android:

NavBarThemeChanging.mp4

iOS:

NavBarThemeChangingiOS.mp4

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Tested the changes where applicable:
  • UWP
  • WinUI
  • iOS
  • Android
  • WASM
  • MacOS
• Updated the documentation as needed:
  • General Doc Update
  • Controls Doc Update
  • Extensions Doc Update
  • controls-styles.md
  • lightweight-styling.md (LightWeight Styling Resource Keys)
• Runtime Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• Contains NO breaking changes
• Associated with an issue (GitHub or internal)
• Commits must be following the Conventional Commits specification.

Other information

Internal Issue (If applicable):

[unodevops]

⚠️⚠️ The build 156217 has failed on Uno Toolkit - CI.