Today, there are many interface functions are using string db name which make the developers easy drop off tenant information by accident.  We need to change these functions to take in DatabaseName object. 

In this ticket, we will change those functions in auth codebase, for example: 

• -buildAuthParams(StringData dbname,..) (broken out to SERVER-80320)

• AuthenticateEvent(StringData mechanism, StringDatadb,...) (this ticket)

• AuthorizationSessionImpl::logoutDatabase(Client* client, StringDatadbname, StringDatareason). (broken out to SERVER-80316)