[colorcorrection] Introduce toggle Night Color shortcut

Summary:
The new shortcut can be useful if a user wants to quickly disable the
Night Color manager for a brief moment.

FEATURE: 409083

Reviewers: KWin, davidedmundson, romangg

Reviewed By: KWin, davidedmundson, romangg

Subscribers: romangg, ngraham, broulik, davidedmundson, kwin

Tags: KWin

Differential Revision: https://phabricator.kde.org/D22287