✨(infra) add celery backend to helm & improvements

* Add a simple celery-backend deployment to helm chart, which
  uses the same docker image as the backend, and runs a single
  worker.
* Update dev keycloack values accordingly
* Update Tiltfile to properly set service dependencies
* Update minio deployment to increase the default max body size limit
  (relevant to uploading files)

src/helm/env.d/dev-keycloak/values.meet.yaml.gotmpl

@@ -83,6 +83,8 @@ backend:
     APPLICATION_BASE_URL: https://meet.127.0.0.1.nip.io
     FILE_UPLOAD_ENABLED: True
     AWS_S3_DOMAIN_REPLACE: https://minio.127.0.0.1.nip.io
+    CELERY_ENABLED: True
+    CELERY_BROKER_URL: redis://default:pass@redis-master:6379/1
 
 
   migrate: