Add event_sync prosody component

[shawnchin]

This prosody component sends HTTP POST request with JSON payload to external API when occupant or room events are triggered.

Ref:

• https://community.jitsi.org/t/trace-user-activity-on-external-systems/102490/7?u=shawn
• Prosody plugin to fire HTTP POST calls on room/occupant events meta#7

[damencho]

I haven't gone through the code, but it will be quicker to ask :) What's the difference between your HTTP request method and https://github.com/jitsi/jitsi-meet/blob/8d562b9d591083f3f0b963c34cb40957d501f109/resources/prosody-plugins/util.lib.lua#L362 ?

[shawnchin]

I actually wrote this about the same time I did the reservations plugin, so they probably use the same method.

If I recall correctly, it is based on http_get_with_retry but with some modifications:

1. non-blocking, so we pass in callback and timeout_callback rather than wait for results
2. takes options table as param so we can pass in customised headers, http method, body, etc
3. uses api_should_retry_for_code so users can influence which http response codes to retry on

Main reason was probably down to having to do POST rather than GET which is what http_get_with_retry does.

I was still learning lua when I wrote that, so might have gotten a bit carried away 😆

[damencho]

Thank you :)