Add support for ACTION_OUTSIDE to Dialog

Historically, Dialogs expected to be fullscreen in order to know when to
close.  By adding support for ACTION_OUTSIDE, they can now close when
the user touches outside of them without actually having to be
fullscreen

Bug: 62373955
Test: cts-tradefed run commandAndExit cts-dev \
      -m CtsAutoFillServiceTestCases -t \
      android.autofillservice.cts.LoginActivityTest#testSaveGoesAwayWhenTouchingOutside
Change-Id: I9cd2afc093ee6f252aaf6c23c029059584879004