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/programs/dconf.nix

@@ -1,7 +1,8 @@
-{ config, lib, ... }:
+{ config, lib, pkgs, ... }:
+
+with lib;
 
 let
-  inherit (lib) mkOption mkIf types mapAttrsToList;
   cfg = config.programs.dconf;
 
   mkDconfProfile = name: path:
@@ -13,6 +14,7 @@ in
 
   options = {
     programs.dconf = {
+      enable = mkEnableOption "dconf";
 
       profiles = mkOption {
         type = types.attrsOf types.path;
@@ -26,9 +28,15 @@ in
 
   ###### implementation
 
-  config = mkIf (cfg.profiles != {}) {
-    environment.etc =
+  config = mkIf (cfg.profiles != {} || cfg.enable) {
+    environment.etc = optionals (cfg.profiles != {})
       (mapAttrsToList mkDconfProfile cfg.profiles);
+
+    environment.variables.GIO_EXTRA_MODULES = optional cfg.enable
+      "${pkgs.gnome3.dconf.lib}/lib/gio/modules";
+    # https://github.com/NixOS/nixpkgs/pull/31891
+    #environment.variables.XDG_DATA_DIRS = optional cfg.enable
+    #  "$(echo ${pkgs.gnome3.gsettings_desktop_schemas}/share/gsettings-schemas/gsettings-desktop-schemas-*)";
   };
 
 }