Expose some more settings in an Advanced dialog

Summary: Was requested by some users who needed these fields and which are already offered by NM.

Test Plan: Changed them, then changed them back.

Reviewers: #plasma, jgrulich

Reviewed By: jgrulich

Subscribers: aspotashev, broulik, ngraham, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D22344