Prevent bounds restoring when user changes them

With IME moving and restoring bounds of the focused tasks,
if a user changes the bounds we shouldn't restore them and leave them as
be.

This cl makes it so that:
1) We store the ImeTarget and it's pre-IME
bounds and post-IME bounds.
2) When IME is disappearing, if any of the IME targets have different
   current bounds then the post-IME bounds, do not restore them to do
previous bounds.

Test: atest DesktopImeHandlerTest
Flag: com.android.window.flags.enable_desktop_ime_bugfix
Bug: 388570293
Change-Id: Id0823a92aec9f17624c40a0e18ae52fd40abe485