Fix a11y for new refactored app handle

With the new WindowDecortation refactor, app handle bound are now
reported to status bar, and status bar has a region excluded for touch
recognition. This allows the app handle to be detected by a11y servcices
without the need of the input layer workaround. The final needed change
is to allow the app handle to handle its own a11y hover events, so that
it can gain focus via touch again.

Bug: 404766889
Test: manually testing
Flag: com.android.window.flags.enable_remove_status_bar_input_layer
Change-Id: I3db6350ed0c169f29f1309bf4df21bc21d03edd5