* 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.
