[Housekeeping] Add [SupportedOSPlatform] to AppBuilderExtensions

[TheCodeTraveler]

Description of Change

This PR adds the [SupportedOSPlatform] attribute to each AppBuilderExtensions file, declaring the minimum supported operating system version for each platform as supported by the .NET MAUI Community Toolkit(s).

This ensures that users are warned immediately when using any CommunityToolkit.Maui.* library that they may be targeting an unsupported version of iOS/Android/Windows/MacCatalyst/Tizen when initializing the toolkit. This PR follows the existing implementation set in CommunityToolkit.Maui.Camera.AppBuilderExtensions.

It's basically an easy way for us to notify developers regrading which platforms we support without requiring them to read the Release Notes.

PR Checklist

• Rebased on top of main at time of PR
• Changes adhere to coding standard

Additional information

The version numbers align with the SupportedOSPlatformVersion noted in each library's csproj:

Maui/src/CommunityToolkit.Maui/CommunityToolkit.Maui.csproj

Lines 21 to 26 in fa4004d

	<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">15.0</SupportedOSPlatformVersion>
	<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'maccatalyst'">15.0</SupportedOSPlatformVersion>
	<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'android'">21.0</SupportedOSPlatformVersion>
	<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</SupportedOSPlatformVersion>
	<TargetPlatformMinVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</TargetPlatformMinVersion>
	<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'tizen'">6.5</SupportedOSPlatformVersion>

This PR also renames CommunityToolkit.Maui.Maps.AppHostBuilderExtension -> CommunityToolkit.Maui.Maps.AppBuilderExtension to align with the naming used in CommunityToolkit.Maui, CommunityToolkit.Maui.Core, CommunityToolkit.Maui.MediaElement and CommunityToolkit.Maui.Camera.

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Files not reviewed (1)

• src/CommunityToolkit.Maui/PlatformConfiguration/AndroidSpecific/NavigationBar.cs: Evaluated as low risk

[ne0rrmatrix]

This is sweet! I am happy to see the build message about versions being put to rest for all those messages.