Fix ConcurrentModificationExceptions during binding.

The same lists of extra items stored in BgModelData are also stored in
UI components. This is causing ConcurrentModificationExceptions. The
solution is to clone these lists or mark them as immutable before storing
them in their respective components.

Bug: 206918543
Test: Verified that crash no longer occurs after fix.
Change-Id: I571a2c451af58137aa7513b372b6a8ecf9bd3ff6