Changed default auto join from NickServ to SASL.

Summary:
NickServ often doesn't function well with auto join, so changed
default to SASL PLAIN. Included message for NickServ, recommending
SASL.

BUG:400362
BUG:397576
BUG:382924

Reviewers: Konversation, psn

Reviewed By: Konversation, psn

Subscribers: psn, Konversation

Tags: Konversation

Differential Revision: https://phabricator.kde.org/D28329