Fix double tapping PIP window when first launch with talkback on

With accessibility services on (e.g. Talkback), user could double tap
to show the pip menu if the state is close (first time launch), but
the a11y focus would set to decor view initially when menu activity
created. We should add the click action on it.

Bug: 152588263
Test: Enable talkback and enter pip mode, double click on pip window
Change-Id: I8270cc3b04c53cc20ba5428a5bfb99224d18c32c