Updating PIP to match UX

- Updating menu actions to match design, fixing issue where
  the actions background would still be visible if there were
  no actions
- Enabling tap-to-show-menu, minimizing, snap-to-edge by default,
  and removing swipe to dismiss option.
- Making the visible size a fixed value instead of a fraction of
  the PIP size

Test: android.server.cts.ActivityManagerPinnedStackTests
Change-Id: Ib767df497ca7bc901c553d35168080f3b737033a
Signed-off-by: Winson Chung <winsonc@google.com>