add standalone clightning-rest service

- Rename `services.rtl.cl-rest` to `services.clightning-rest`.
  `clightning-rest` is generally useful for connecting external REST clients
  to clightning.

- Add a dedicated network namespace in netns-isolation.

- Add nodeinfo entry.

- Add datadir (which contains REST auth data) to backups.

modules/presets/enable-tor.nix

@@ -38,6 +38,7 @@ in {
     rtl = defaultEnforceTor;
     joinmarket = defaultEnforceTor;
     joinmarket-ob-watcher = defaultEnforceTor;
+    clightning-rest = defaultEnforceTor;
   };
 
   # Add onion services for incoming connections