Fix drag and drop (1/3)

Added ability to send different InputWindowCommands to SurfaceFlinger. Also
added transferTouchFocus function from client so it can be translated to an
InputWindowCommand and passed to SF.

Bug: 120463595
Test: Builds, no uses of new function
Change-Id: I17deaf4a96d5a5bf6b14795d66419acffdb10882
9 files changed