Add trim margins and trim to selection icons

Summary:
BUG: 401489

FIXED-IN: 5.55

Add `trim-margins` and `trim-to-selection` action icons.

Test Plan:
{F6569208}
With Breeze-dark theme:
{F6569209}

Reviewers: #vdg, ngraham, ndavis

Reviewed By: #vdg, ngraham, ndavis

Subscribers: ndavis, ngraham, kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D18552