Current implementation of kdeconnect-handler did not support controlling the function of kdeconnect-handler completely through GUI.
This patch enables that by adding knobs to the GUI and doing necessary changes to the cpp.
We use kdeconnect-version.h in several places and therefore it needs to be in the include path. We currently do this by setting target_include_path in a few places. Replace this with an interface library that we can link against that sets up the correct include path. IMO it is cleaner this way.
Summary: Makes it possible to handle tel urls with any KDE Connect device
Test Plan: Manual testing
Reviewers: #kde_connect, albertvaka, nicolasfella
Reviewed By: #kde_connect, nicolasfella
Subscribers: nicolasfella
Differential Revision: https://phabricator.kde.org/D6120
