SELinux: split property_contexts into platform and non-platform components.

Bug: 33746484
Test: Successfully boot with original service and property contexts.
      Successfully boot with split serivce and property contexts.

Change-Id: I1932684f600dd34d5136e72ac053fae13f0c3eba
Signed-off-by: Sandeep Patil <sspatil@google.com>