Add more fixes to BottomNavigationView.

- Fixes crash for fast taps of buttons where
  BottomNavigationItemView#getAnimator returns null since the view
  is already in the correct state.
- Added checks for illegal menus
  - Max menu item check 5 items
  - No submenus
- Updated the sizing of the BottomNavigationItemView.
- Adding missing getItemBackgroundResource method.

Bug: 27675079

Change-Id: I856d250d92e69925a75cf4996a1d02f91441d67c
4 files changed