Add 16:9 crop preset to Gwenview

Summary:
BUG: 364007

Add a 16:9 crop preset.

Test Plan:
Tested in KDE Neon (dev unstable). Works fine:

{F3903510}

Reviewers: #kde_applications, aacid, broulik, cfeck

Reviewed By: broulik

Differential Revision: https://phabricator.kde.org/D7739