Explicitly target iOS and macOS to osx and Windows platforms (only)

[matt-goldman]

Description of Change

Adds MS Build conditions to explicitly exclude macOS and iOS TFMs when the OS is not macOS or Windows.

No tests included as it would require adding a new workflow with a Linux-targetted runner specifically just for this one test. That's probably not necessary; however could be useful in future as would allow building Android (and Tizen) binaries on a Linux runner. Might be worth considering, but for now I did not want to introduce a workflow just for that.

Linked Issues

• Fixes [BUG] Does not compile on Linux #3185

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: N/A - not related to public docs. I also checked the contributing guide and there was nothing there to update.

Additional information

Just confirming that this is a no-op for any existing users, and just enables development on Linux.

[Copilot]

Pull request overview

This PR updates the repo-wide MSBuild configuration to avoid including Apple TFMs when building on unsupported host OSes (e.g., Linux), enabling developers to build Android (and optionally Tizen) without requiring iOS/macOS workloads.

Changes:

• Add a conditional PropertyGroup in Directory.Build.targets to override TargetFrameworks on non-macOS/non-Windows hosts when iOS is present.
• Ensure Exe projects only target Android in that scenario, with optional Tizen inclusion.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.