Protect Bluetooth OPP ACCEPT and DECLINE broadcast

Non-system apps could send these, and accept OPP transfers without user
interaction.

Test: run POC code, see that it crashes instaed of accepting
Bug: 35258579
Change-Id: I37bf2e17b4d612258f9dbaa879727ac7c72e5969
(cherry picked from commit 52c8ba1ecff872ea425d58b37afc1d55528b95f8)