♻️(y-provider) replace y-webrtc-signaling by server-y-provider

We replace the y-webrtc-signaling app by
the server-y-provider server.
The server-y-provider server uses @hocuspocus to
do collaborative editing on docs.

src/frontend/package.json

@@ -5,7 +5,8 @@
   "workspaces": {
     "packages": [
       "apps/*",
-      "packages/*"
+      "packages/*",
+      "servers/*"
     ]
   },
   "scripts": {