This is far less code and allows for an easier enforcing of standards, for
example the name of the log identifiers which were adjusted in a few cases.
Also clean up unused includes when noticed.
* Moves the XML definitions of DBus interfaces and code generation from the different plugins
to kdeconnectinterfaces. Before each plugin had their own, some of them duplicated.
* Appends `// clazy:skip` to the generated interface files, so Clazy doesn't emit warnings
about them because they are missing the NOTIFY/CONSTANT keywords on Q_PROPERTIES.
* Makes kdeconnectinterfaces static on Qt5 as well (removes a difference with Qt6).
* Moves the generated files to a `generated` directory and updates the includes so they are
easily distinguished from other header files.
The moc process already rebuilds the plugin when the JSON file changes, consequently the additional parameter is not needed.
Task: https://phabricator.kde.org/T14649
