Add DISMISS_NOTIFICATION_SHADE action for a11y

As discussed in b/159334261, although the current a11y use-cases for
closing the notification shade are already handled, it makes sense to
add an explicit global action for accessibility services to close the
notification shade (especially given there is one for opening the shade
already).

Added dependency to SystemActions, which required me to change add
SystemActions to SystemUIGoogleBinder (topic). I also added to
CarSystemUIBinder since SystemActions was also in their xml. I don't
know if I need to add to others (eg. Arc), please advise.

Bug: 159334261
Bug: 159105552
Test: With the shade opened, as a11y service send
      GLOBAL_ACTION_DISMISS_NOTIFICATION_SHADE and verify shade is
      closed.
Change-Id: If52a1763170d5a5efd6b4756794206fd8bfb18a0