Add-app-to-panel string overhaul.
Summary:
- Get rid of the unwieldy "Show a launcher when not running" and use Pin instead
- Clarify that "Add to Panel" adds a widget to distinguish from adding to Task Manager
- Use "Pin to Task Manager" in launchers as well
Often-discussed, often-desired, VDG-approved.
BUG:368549
Reviewers: Plasma, mart, broulik
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D3948