🔒️(helm) add pod and container securityContext

This commit aim at adding a securityContext for
pod and container in Deployment and Job,
it include livekit pods as well

It adds 2 values :
- podSecurityContext : for pods
- securityContext : for containers

Please note that `celeryBackend` Deployment does
not have any values defined in `values.meet.yaml` at the moment.

src/helm/env.d/common.yaml.gotmpl

@@ -0,0 +1,38 @@
+.podSecurityContext: &podSecurityContext
+  runAsUser: 1000
+  runAsGroup: 1000
+  fsGroup: 1000
+  fsGroupChangePolicy: "OnRootMismatch"
+  runAsNonRoot: true
+  seccompProfile:
+    type: RuntimeDefault
+
+.securityContext: &securityContext
+  allowPrivilegeEscalation: false
+  capabilities:
+    drop:
+      - ALL
+
+frontend:
+  podSecurityContext: *podSecurityContext
+  securityContext: *securityContext
+
+backend:
+  podSecurityContext: *podSecurityContext
+  securityContext: *securityContext
+
+summary:
+  podSecurityContext: *podSecurityContext
+  securityContext: *securityContext
+
+celeryTranscribe:
+  podSecurityContext: *podSecurityContext
+  securityContext: *securityContext
+
+celerySummarize:
+  podSecurityContext: *podSecurityContext
+  securityContext: *securityContext
+
+agents:
+  podSecurityContext: *podSecurityContext
+  securityContext: *securityContext