Note that Freshdesk allows custom templating for outgoing payloads
in their webhook UI. Therefore, the payloads added in this commit
did not have to be official payloads from Freshdesk.
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.
Anders Kaseorg
Eeshan Garg