(4/n) Shift to oneway binder call for register key handler

handleKeyGestureEvent() is synchronous API that makes system server
dependent on handler and can cause ANR if handlers misbehave.
As a replacement, handlers should provide list of gesture they want
to listen to. For consistency, we only allow single handler per
gesture.

Test: atest InputTests
Test: atest WmTests
Test: Presubmit
Bug: 358569822
Bug: 383602794
Flag: EXEMPT refactor
Change-Id: Iea0f6ba3360ed241e19f0265d6ab28fd7889aafa