kwayland 5.70.0 Qt-style API to interact with the wayland client and server

As the names suggest they implement a Client respectively a Server API for the Wayland protocol. The API is Qt-styled removing the needs to interact with a for a Qt developer uncomfortable low-level C-API. For example the callback mechanism from the Wayland API is replaced by signals, data types are adjusted to be what a Qt developer expects - two arguments of int are represented by a QPoint or a QSize.