Run a main looper

Instead of blocking the main thread until completion, run a looper.

This will allow the main thread to process any event posted to the main
looper.

Refs #6009 comment <https://github.com/Genymobile/scrcpy/pull/6009#issuecomment-2940810736>
PR #6129 <https://github.com/Genymobile/scrcpy/pull/6129>