Add tool used to verify dialog behaviors.

We wrote this tool several months ago to exercise all the various
permutations of MediaStore dialogs, but never merged it into the
tree until now.  This is typically used by PM, UX, and a11y teams
to verify behaviors in various edge cases.

Bug: 156257943
Test: manual
Change-Id: Ib301298d77028d0854ec4ac4c2e8cb2047156a89
3 files changed