Make less known wayland compositors usable (#32285)

* bemenu: init at 2017-02-14

* velox: 2015-11-03 -> 2017-07-04

* orbment, velox: don't expose subprojects

the development of orbment and velox got stuck
their subprojects (bemenu, dmenu-wayland, st-wayland) don't work correctly outside of parent projects
so hide them to not confuse people
swc and wld libraries are unpopular and unlike wlc are not used by anything except velox

* pythonPackages.pydbus: init at 0.6.0

* way-cooler: 0.5.2 -> 0.6.2

* nixos/way-cooler: add module

* dconf module: use for wayland

non-invasive approach for #31293
see discussion at #32210

* sway: embed LD_LIBRARY_PATH for #32755

* way-cooler: switch from buildRustPackage to buildRustCrate #31150

nixos/modules/module-list.nix

@@ -104,6 +104,7 @@
   ./programs/tmux.nix
   ./programs/venus.nix
   ./programs/vim.nix
+  ./programs/way-cooler.nix
   ./programs/wireshark.nix
   ./programs/xfs_quota.nix
   ./programs/xonsh.nix