Summary:
The RemotecommandsPlugin lacks a graphical frontend.

Inlcudes a Dbus Interface for fetching the commands and a Model exposing them to QML. For this I oriented on the NotificatonsPlugin.

Test Plan:
Open command list in app, check available commands, trigger some. Do same for CLI.
Activate edit action, check KCM opening on remote device, add command, check for new command in list

Reviewers: #kde_connect, apol

Reviewed By: #kde_connect, apol

Subscribers: apol, kdeconnect, #kde_connect

Tags: #kde_connect

Differential Revision: https://phabricator.kde.org/D13503