Declare arrays as static
Fix SASL logic error

When we were using a client-side certificate, Textual would ask whether
we had permission to use SASL EXTERNAL as an identification mechanism.
However, this logic was broken.

“self.config.sendAuthenticationRequestsToUserServ” was being called in
place of “self.config.saslAuthenticationUsesExternalMechanism” — this
is a result of the fast paced v5 refactoring and my lack of quality
control.