Mdm::Service text fields search

[MSP-10035](https://jira.tor.rapid7.com/secure/RapidBoard.jspa?rapidView=84&selectedIssue=MSP-10035)

Add search operators for `Mdm::Service#info` and `Mdm::Service#proto`.
Search attributes with a `:type` of `{set: *}` use the a class method `<attribute>_set` to get the set of allowed values when the operation is validating the formatted value is in the set of allowed values.

[Metasploit::Model::Search::Operation::Set#membership](https://github.com/rapid7/metasploit-model/blob/e46160384754ebc1a6778ad6432f03bd495df454/app/models/metasploit/model/search/operation/set.rb#L12-L33) validates that [Metasploit::Model::Search::Operator::Attribute#attribute_set](https://github.com/rapid7/metasploit-model/blob/e46160384754ebc1a6778ad6432f03bd495df454/app/models/metasploit/model/search/operator/attribute.rb#L52-L57), which is `<attribute>_set` (i.e. `proto_set`) on [Metasploit::Model::Search::Operator::Base#klass](https://github.com/rapid7/metasploit-model/blob/e46160384754ebc1a6778ad6432f03bd495df454/app/models/metasploit/model/search/operator/base.rb#L13-L17) (i.e.`Mdm::Service`)