wpaperd: add systemd service; move to services/ from programs/ (#6302)

This commit adds a systemd service to run it, and accordingly moves it to services.wpaperd.

In addition, the existing tests have been migrated to services, and an entry in the newslist has been created alerting users to this change.

modules/programs/wpaperd.nix

@@ -1,49 +0,0 @@
-{ config, lib, pkgs, ... }:
-
-with lib;
-
-let
-  cfg = config.programs.wpaperd;
-  tomlFormat = pkgs.formats.toml { };
-in {
-  meta.maintainers = [ hm.maintainers.Avimitin ];
-
-  options.programs.wpaperd = {
-    enable = mkEnableOption "wpaperd";
-
-    package = mkPackageOption pkgs "wpaperd" { };
-
-    settings = mkOption {
-      type = tomlFormat.type;
-      default = { };
-      example = literalExpression ''
-        {
-          eDP-1 = {
-            path = "/home/foo/Pictures/Wallpaper";
-            apply-shadow = true;
-          };
-          DP-2 = {
-            path = "/home/foo/Pictures/Anime";
-            sorting = "descending";
-          };
-        }
-      '';
-      description = ''
-        Configuration written to
-        {file}`$XDG_CONFIG_HOME/wpaperd/wallpaper.toml`.
-        See <https://github.com/danyspin97/wpaperd#wallpaper-configuration>
-        for the full list of options.
-      '';
-    };
-  };
-
-  config = mkIf cfg.enable {
-    home.packages = [ cfg.package ];
-
-    xdg.configFile = {
-      "wpaperd/wallpaper.toml" = mkIf (cfg.settings != { }) {
-        source = tomlFormat.generate "wpaperd-wallpaper" cfg.settings;
-      };
-    };
-  };
-}