Add flag for fixing return of show/hide input

Flag that hguards compatibility change for sync/async nature of
IMM#show/hideSoftInput() when using zeroJankProxy.

Flag: compatchange_for_zerojankproxy
Bug: 352594277
Test: manual build.

Change-Id: Ie4194051af941cbc1618992232cfe7463e310d53
1 file changed