Support mac_arm64 host only test configuration

Create `mac_arm64` configuration for host-only tests to be run on arm Macs, similar to:
https://github.com/flutter/flutter/blob/4b1ff134596196d31d5b324ecb997ac0340187db/.ci.yaml#L49-L56

For example, `Mac_arm64_ios macos_chrome_dev_mode` does not need a tethered iOS device to pass.

cc @keyonghan 