Ship local copy of plasma-window-management protocol spec
plasma-wayland-protocols and kwayland have different release cycles, which causes CI issues and dependency-wise it's somewhat fragile.
This change adds a local copy of the plasma-window-management protocol spec to break the dependency relationship between plasma-wayland-protocols and kwayland projects. The proposed approach is counter-productive because we have to copy protocol spec files.
On the other hand, kwayland already has local copies of other plasma specific protocols.