conditionalize authentication handling based on service version

[radhermit]

Newer versions of Bugzilla support more secure methods of authentication that should be used.

To do this properly while supporting a decent amount of Bugzilla versions, the service version will have to be requested initially during service creation. Then the auth injection method can conditionalize how it handles based on the version's supported functionality.

[radhermit]

Actually, this isn't going to be as feasible to do it based on the service version since some official servers (e.g. https://bugzilla.mozilla.org) run custom, patched instances that support X-BUGZILLA-API-KEY or HTTP bearer auth headers. So instead it might be worth having a feature-based enum that can be deserialized from the config settings to denote what functionality a given service provides.

This can also provide support for vanilla service functionality as different versions would support different sets of features, with server specific ones not being enabled by default for any version.