scripts: add wl_compcheck.py

scripts: add wl_compcheck.py

Simple utility to allow protocol and version comparison between different
running compositors. This can be used to detect missing protocols or
versions in labwc. See for example this result when running against the
current labwc master and sway 1.10 (nested, results on DRM may differ):

  Protocols missing from labwc @ wayland-0
  ext_transient_seat_manager_v1                   1
  wl_compositor                                   6  (has version 5)
  wp_alpha_modifier_v1                            1
  wp_content_type_manager_v1                      1
  xdg_wm_base                                     5  (has version 3)
  zwp_keyboard_shortcuts_inhibit_manager_v1       1

  Protocols missing from sway @ wayland-1
  wl_drm                                          2
  zcosmic_workspace_manager_v1                    1