Allow to show IME snapshot on home when turning off screen

Change [1] adds IME snapshot for keeping IME on apps when switching
tasks. Home task was excluded from the target to attach IME snapshot
because home doesn't have the navigation cases as regular task.

Change [2] assumes if IME snapshot should show, then the real IME
should be hidden. The current caller is from
ImeVisibilityStateComputer#onInteractiveChanged with !interactive.

If IME is hidden immediately without showing the snapshot, it will
look flickering.

[1]: I6bef36c779a28777408576f57e5d1c67d5d48e3f
[2]: I2e1e4bc106fc14aa65825ee82dc09390422951c5

Bug: 330713465
Test: Press search bar on home. Turn off screen.
      IME won't be flickering.
Change-Id: I1132a78ba1154e777a9751ac70659cd6377fcb39