feat: watcher process for cleaning up after crashes

[lars-berger]

• On startup, spawn a 2nd instance of the current executable (ie. GlazeWM.exe) with a special flag to indicate that the watcher logic should be run for this new process.
  • Create new project GlazeWM.App.Watcher containing the logic for the watcher. The watcher keeps track of managed window handles and on disconnect from the main process IPC server (eg. due to a crash), it restores all managed handles.
  • On window manage/unmanage, emit WindowManagedEvent and WindowUnmanagedEvent.