Split new NEARBY_DEVICES permissions

This creates a "split permission" from:
- BLUETOOTH to BLUETOOTH_SCAN and BLUETOOTH_CONNECT, and
- BLUETOOTH_ADMIN to BLUETOOTH_SCAN and BLUETOOTH_CONNECT
...for apps targetting SDK<31.

What this means is that any apps that use either the BLUETOOTH or the
BLUETOOTH_ADMIN permission, and target SDK<31, will automatically be
be granted the BLUETOOTH_SCAN and BLUETOOTH_CONNECT permissions.

Bug: 181813006
Test: manual
Change-Id: I92a974203fd51e87747e740273a21ba399a81cd0