Solid-device-automounter/kcm: Enable/Disable columns automount onLogin/onAttached depending on corresponding checkbox

Summary: To make clear to the user what automount options imply.

Test Plan:
Before:

After:

Reviewers: Plasma, ervin, ngraham, broulik, bport, crossi

Reviewed By: ervin

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D27057