nixos/nextcloud: add occ in path of nextcloud-setup

This makes possible to use nextcloud-occ for setting extra
configuration options.

Example:

  systemd.services.nextcloud-setup = {
    script = mkAfter ''
      nextcloud-occ config:system:set redis 'host' --value '/var/run/redis/redis.sock' --type string
      nextcloud-occ config:system:set redis 'port' --value 0 --type integer
    '';
  };

nixos/modules/services/web-apps/nextcloud.nix

@@ -390,6 +390,7 @@ in {
         in {
           wantedBy = [ "multi-user.target" ];
           before = [ "phpfpm-nextcloud.service" ];
+          path = [ occ ];
           script = ''
             chmod og+x ${cfg.home}
             ln -sf ${pkgs.nextcloud}/apps ${cfg.home}/