Update to metasploit-credential to use gem.

MSP-10808
Use metasploit-credential with association search

MSP-10029
Fix version restrictions on metasploit-credential

MSP-10029

The '<' version should have been '0.8' and not '0.7.10' because '0.8' is
the next incompatible version number.
Update metasploit_data_models and metasploit-credential for tag search

MSP-10029

Use metasploit_data_models that supports searching Mdm::Tag and a
compatible metasploit-credential.  Needed so
Metasploit::Credential::Core#tags can be searched in Pro.
Update spec to handle Mdm::Service#proto sequence

MSP-10029

Mdm::Service factories were changed in metasploit_data_models 0.19.0 to
use a sequence that cycles between 'tcp' and 'udp'.  To make the spec
clearer, just hard-code the protos under test instead of relying on
default behavior.
Merge branch 'feature/MSP-10029/core-search' into staging/electro-release

Support search