🏗️(y-provider) organize yjs server

Many routes were in the server.ts file, now they
are in their own files in the handlers folder.
The server.ts file is now AppServer that handles
the routes.
We split as well the tests.

src/frontend/servers/y-provider/package.json

@@ -7,7 +7,7 @@
   "type": "module",
   "scripts": {
     "build": "tsc -p tsconfig.build.json && tsc-alias",
-    "dev": "nodemon --config nodemon.json",
+    "dev": "cross-env COLLABORATION_LOGGING=true && nodemon --config nodemon.json",
     "start": "node ./dist/start-server.js",
     "lint": "eslint . --ext .ts",
     "test": "jest"
@@ -34,6 +34,7 @@
     "@types/supertest": "6.0.2",
     "@types/ws": "8.5.13",
     "eslint-config-impress": "*",
+    "cross-env": "*",
     "jest": "29.7.0",
     "nodemon": "3.1.9",
     "supertest": "7.0.0",