Migrate to using DisplayLayout instead of DisplayInfo

- No need to keep two sources of truth, can just use display
  layout to  store/calcualte all the info we need
- Update the display layout on display configuration changed
  as well
- KI: When changing displays, the min size of the pip also
  changes so we will need to calculate that based on the
  smallest display size

Bug: 175644531
Test: atest PinnedStacktests
Test: atest WMShellUnitTests
Change-Id: I34614a8f739311c7b382b6848e4752fa68c91cfb