Move home stack forward while entering split-screen in some cases

If the home activity if the top split-screen secondary stack, then the
primary split-screen stack is in the minimized mode which means it can't
receive input keys, so we should move the focused app to the home app so
that window manager can correctly calculate the focus window that can
receive input keys.

Change-Id: If7379d6259e0f589cae03f235a4cc7d03cc41e52
Fixes: 73349992
Test: Steps from bug