nixos/nix-daemon: Move to services/system

It is now only about the system service.
Granted, it also installs the client package, but that could be
factored out later, with actual test to support such a new type of
configuration.

Changed files
+1 -1
nixos
modules
+1 -1
nixos/modules/module-list.nix
···
./services/misc/moonraker.nix
./services/misc/n8n.nix
./services/misc/nitter.nix
-
./services/misc/nix-daemon.nix
./services/misc/nix-gc.nix
./services/misc/nix-optimise.nix
./services/misc/nix-ssh-serve.nix
···
./services/system/earlyoom.nix
./services/system/kerberos/default.nix
./services/system/localtimed.nix
+
./services/system/nix-daemon.nix
./services/system/nscd.nix
./services/system/saslauthd.nix
./services/system/self-deploy.nix
nixos/modules/services/misc/nix-daemon.nix nixos/modules/services/system/nix-daemon.nix