Fix platformFilter usage for single filters

[kwridan]

Part of #5381

Short description 📝

• XcodeProj format supports both a single platformFilter and multiple platformFilters (plural) attribute with the project file format
• the singlular attribute appears to only be used for ios and maccatalyst while for all other filters, the plural form is used (even when specifying a single filter)
• Xcode doesn't recognize the other filters such as tvos or macos when provided to platformF ilter
• Xcode does support ios and maccatlyst when using the plural form however immediatley revert s it back to platformFilter causing an unstable generated project
• To mitigate this those filters are explicitly specifed as the ones that can be used with the si ngle platformFilter

How to test the changes locally 🧐

• platformFilters are not yet exposed via public API as such inspection via manually creating a p roject with a multi-platform target, apply filters and verify which attributes are in use to veri fy

Contributor checklist ✅

• The code has been linted using run make workspace/lint-fix
• The change is tested via unit testing or acceptance testing, or both
• The title of the PR is formulated in a way that is usable as a changelog entry
• In case the PR introduces changes that affect users, the documentation has been updated

Reviewer checklist ✅

• The code architecture and patterns are consistent with the rest of the codebase
• Reviewer has checked that, if needed, the PR includes the label changelog:added, changelog:fixed, or changelog:changed, and the title is usable as a changelog entry

[waltflanagan]

Thanks for investigating how Xcode was dealing with these values. it was extremely confusing why things werent working with the multiplatform work.