Uinput: Add sync command to get a response when the command is processed

Bug: 291881033
Bug: 294275314
Test: manual
Change-Id: Ie522ff44aa1cb7ceb7f21a23d6dd68efd1845f7c
Merged-In: Ie522ff44aa1cb7ceb7f21a23d6dd68efd1845f7c
4 files changed