Add some move constructors and assignment operators to CameraMetadata.

This avoids unnecessary copying of camera metadata which can get
expensive in cases of large camera metadata blobs.

Bug: 71727540

Test: GCA (sanity)
Test: Add CallStack::logStack() in CameraMetadata's move asignment
      operator -> see that it gets called for every insertResultLocked.

Change-Id: I6c75c7ce5267126916c865b028e5f7c7f50b763b
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>