Fix NPE in TelecomManager#isOutgoingCallAllowed

There is a potential for a NPE if "excludeCall" is null.  Adding null
check and unit tests to verify operation of the isOutgoingCallAllowed API,
as well as basic outgoing self-managed calls (which rely on this API).

Test: Added unit tests.
Change-Id: Ia5e92a7cb418af0d131daa2ca88b7cd4d36ab057
Fixes: 67495237