The labels of clipboard ROM and clipboard report sessions of WM clients
must be consistent with the client's nitpicker label. Hence, we must
route those sessions through the window manager, analogously to the
approach taken for shape reports in #3165.
Issue #3437
This commit moves the window layouter and window decorator into
dedicated packages that can now be combined with the "wm" server at
runtime and restarted/reconfigured/swapped-out independently.
To use the window manager, one must start the 'wm', 'window_layouter',
and one of the 'motif_decorator' or 'themed_decorator' subsystems.
Fixes#3024
