Include the iOS, Android, and macCatalyst supported platforms

[jeffhandley]

With dotnet/sdk#16489, we are removing iOS, Android, and macCatalyst from the default set of supported platforms that will be checked by the Platform Compatibility Analyzer. We intend to reintroduce those platforms into a default set with scoping to cover libraries; that will be handled by dotnet/sdk#16488. To ensure no gap in coverage of these platforms in dotnet/runtime though, this change explicitly adds those platforms back into our own build. These platforms are added in unconditionally as they were in the SDK default so that we maintain full continuity of that coverage.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[ghost]

Tagging subscribers to this area: @Anipik, @safern, @ViktorHofer
See info in area-owners.md if you want to be subscribed.

Issue Details

---

With dotnet/sdk#16489, we are removing iOS, Android, and macCatalyst from the default set of supported platforms that will be checked by the Platform Compatibility Analyzer. We intend to reintroduce those platforms into a default set with scoping to cover libraries; that will be handled by dotnet/sdk#16488. To ensure no gap in coverage of these platforms in dotnet/runtime though, this change explicitly adds those platforms back into our own build. These platforms are added in unconditionally as they were in the SDK default so that we maintain full continuity of that coverage.

Author:	jeffhandley
Assignees:	-
Labels:	area-Infrastructure-libraries
Milestone:	-

[marek-safar]

Should this be unified with the logic bellow and disable them for tests?

[jeffhandley]

I considered that, but thus far we've been OK having these platforms enabled for tests. I didn't want to loosen up any more than necessary, as that could add risk of dotnet/sdk#16488 introducing new warnings.