add dynamic config field for requiring/not requiring whitelist (#6355)

## Summary

Adds FF to toggle whitelist gating on client.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6355-add-dynamic-config-field-for-requiring-not-requiring-whitelist-29b6d73d36508172b7c2f6f65f6b8a65)
by [Unito](https://www.unito.io)

src/platform/remoteConfig/types.ts

@@ -14,6 +14,7 @@ type ServerHealthAlert = {
  */
 export type RemoteConfig = {
   mixpanel_token?: string
+  require_whitelist?: boolean
   subscription_required?: boolean
   server_health_alert?: ServerHealthAlert
 }