[Windows Arm64] Add build-only Arm64 CI to flutter/packages #129813
Description
Background
Flutter is being updated to support Windows Arm64: https://flutter.dev/go/windows-arm64
Work
- Add build-only Arm64 CI to flutter/packages for master channel
- Wait until the next Flutter stable release so that the Windows build directory update migration is on stable channel
- Add build-only Arm64 CI to flutter/packages for stable channel
- Promote out of
bringup. See: [Devicelab] Add Windows Arm64 machines to the non-staging pool #134083