✨(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/extra/templates/minio.yaml

@@ -3,6 +3,8 @@ apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
   name: minio
+  annotations:
+    nginx.ingress.kubernetes.io/proxy-body-size: 10m
 spec:
   rules:
   - host: "minio.127.0.0.1.nip.io"