Needs to respect Discord ratelimits

The sender code should read and respect Discord rate-limit Headers to prevent lost webhooks.

### Dev notes
In this file: https://github.com/CFC-Servers/cfc_err_forwarder/blob/main/moon/cfc_err_forwarder/discord_interface.moon
It needs to return a function that queues the error for sending, and then start a queue processor that sends the errors as fast as the response headers allow it.