mmcli: allow running `--3gpp-profile-manager-set` with more than one APN type specified in the "apn-type" key.
This is currently not working properly because mm_common_get_apn_type_from_string()
returns one single flag value as matched in _flags_from_string()
.
We could probably make this _flags_from_string()
receive an additional argument specifying whether we should match single values or a bitmask. For the APN type we do want a bitmask, but for other things like IP type we want to match single values.