Implement backup and restore of input gesture customizations

Test: atest InputTests:KeyGestureControllerTests
Test: Manually tested backup + restore on device
Bug: 365064144
Bug: 382184249
Flag: com.android.hardware.input.enable_backup_and_restore_for_input_gestures

Change-Id: Iff0358fd2f4cd8efa7adde103befc70017871d7f