[KMoreTools] Enable installing tools via appstream url

Summary:
When a tool is not installed add an action to trigger the appstream url if available. This allows installing via Discover or other software stores.

Add GParted url as example. More urls should be added.

Test Plan: Install GParted from Dolphin

Reviewers: Frameworks, gregormi, dhaumann, ngraham

Reviewed By: gregormi, ngraham

Subscribers: ngraham, dhaumann, kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D13706