Add CONNECTIVITY_INTERNAL to bt tethering related APIs temporarily

Some NetworkManagementService APIs are still called by bluetooth
tethering. But it's not good to give bluetooth app NETWORK_STACK
due to NETWORK_STACK is extremly powerful permission that can
access most of all networking functions. So add
CONNECTIVITY_INTERNAL to those APIs which are called by bluetooth
tethering temporarily.

Bug: 32963470
Test: atest FrameworksNetTests
Change-Id: Ib3a4acf3018a52ef38e78d9e2a702af3fef026d4