Fixed an issue where all documents were include regardless of MultiTarget support

[Arlodotexe]

PR Type

Fixes an issue where all documents were include regardless of MultiTarget support.

• Bugfix

What is the current behavior?

Before, the tooling would blindly pull in all markdown files and let the SampleGen source generator sort it out for creating the Document Registry.

This is in contrast to the Sample Registry, which inherits its MultiTarget-aware characteristics from MSBuild by discovering only in projects that are referenced at build time.

What is the new behavior?

With these changes, markdown files are preprocessed with the new Target. Files found in components that don't <MultiTarget> the platform being built are filtered out before being added as AdditionalFiles. Then, it's picked up by the SampleGen tooling to create the Document Registry.

PR Checklist

Please check if your PR fulfills the following requirements:

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest main branch of toolkit
• Tested code with current supported SDKs
• New component
  • Documentation has been added
  • Sample in sample app has been added
  • Analyzers are passing for documentation and samples
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• Tests for the changes have been added (if applicable)
• Header has been added to all new source files
• Contains NO breaking changes

Other information

[michael-hawker]

I may have to try another machine, I haven't been able to get past unoplatform/Uno.Wasm.Bootstrap#776 building this at the moment.

[michael-hawker]

@Arlodotexe tested this against the latest changes in the CommunityToolkit/Tooling-Windows-Submodule#141 PR that this is on top of, this PR needs to be updated though, but otherwise, good to go.

[michael-hawker]

Tested this earlier with the submodule changes, so should be all good, thanks!