For Swift Package Manager to work with macOS, the macOS engine artifact needs to be an xcframework.

• [engine] Create FlutterMacOS.xcframework and archive it: Build macOS engine as an xcframework engine#50300
• [tool] Replace usage of FlutterMacOS.framework artifact with new FlutterMacOS.xcframework artifact
  • Ensure codesigning: Add FlutterMacOS.xcframework artifact #143244
• [tool] Stop building the xcframework on flutter build macos-framework and instead use the one in the artifact cache: Add FlutterMacOS.xcframework artifact #143244
• [engine] Remove FlutterMacOS.framework archive
  • Before the old FlutterMacOS.framework can be removed, we'll need to let the Flutter release team know so they can update their roll scripts, and coordinate with the Fl@G team to make sure build rules are updated, if needed.

Example of when it was done for iOS: #60109