Now, every line in the commit log is properly quoted, but using a Zulip markdown block quote (rather than just a single `>`). Fixes: #9792
All webhook fixtures have now been renamed from <webhook_name>/fixtures/<webhook_name>_<event_type>.json to <webhook_name>/fixtures/<event_type>.json.
All webhook fixtures in zerver/fixtures/<webhook_name> have now been moved to dedicated webhook-specific directories under zerver/webhooks/<webhook_name>/fixtures, where <webhook_name> is the name of the webhook.