New icon for KTimeTracker

Summary:
This diff adds a new icon for KTimeTracker.

T12305

BUG: 410708

Test Plan: {F7927315}

Reviewers: #vdg, ndavis

Reviewed By: #vdg, ndavis

Subscribers: hellcp, ndavis, kde-frameworks-devel, aspotashev

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D26441