Add "not supported" string for MMI codes not supported by network.

When either the GSM or IMS MMI codes result in a "request not supported"
or "operation not allowed" result code, report that the operation is not
supported.

Bug: 230841132
Test: Added new unit tests to verify the correct message is generated
when the network reports that a feature is not supported.

Change-Id: I30af9525a02880be83c70e66c36b28ec1b72eddf
Merged-In: I30af9525a02880be83c70e66c36b28ec1b72eddf