Revert "Revert "Allow transient taskbar to unstash over soft ime""

This reverts commit c8c81a34.

Reason for revert: fix tests by not auto stashing when ime comes up, but still allow taskbar to show if user initiaties it

Bug: 255818649
Change-Id: Id3ab27dcc205e5a72dbd0481e3eabc10b2e1b643
Test: pull up ime, swipe to reveal taskbar