🔧(backend) add COLLABORATION_SERVER_URL setting

The frontend need to know the collab server url,
so we need to add a new setting to the backend,
in order to expose this value to the frontend.
If the setting is not defined, the frontend current
domain will be used as the base url.
In production this setting do not need to be defined
since we have nginx capturing the ws requests,
but in development we need to define it to target
the collaboration server.

env.d/development/common.dist

@@ -45,3 +45,6 @@ OIDC_AUTH_REQUEST_EXTRA_PARAMS={"acr_values": "eidas1"}
 AI_BASE_URL=https://openaiendpoint.com
 AI_API_KEY=password
 AI_MODEL=llama
+
+# Collaboration
+COLLABORATION_SERVER_URL=ws://localhost:4444