♻️(frontend) frontend environment free

Until now, the front had to know at build time
the url of the backend and the webrtc server
to be able to communicate with them.
It is not optimal because it means that we need
multiple docker image (1 per environment) to have
the app working, it is not very flexible.

This commit will make the frontend "environment free"
by determining these urls at runtime.

src/helm/env.d/dev/values.impress.yaml.gotmpl

@@ -50,7 +50,8 @@ backend:
 frontend:
   envVars:
     PORT: 8080
-    NEXT_PUBLIC_API_URL: https://impress.127.0.0.1.nip.io/api/v1.0/
+    NEXT_PUBLIC_API_ORIGIN: https://impress.127.0.0.1.nip.io
+    NEXT_PUBLIC_API_URL: /api/v1.0/
     NEXT_PUBLIC_SIGNALING_URL: wss://impress.127.0.0.1.nip.io/ws
 
   replicas: 1