Feature Request: Implement srt_listen_callback()

[eric]

In reading https://github.com/Haivision/srt/blob/master/docs/AccessControl.md it discusses what can be done in the srt_listen_callback() to customize the connection based on the Stream ID. It would be nice to have this control from the golang bindings.

[jeoliva]

Done by @iSchluff and merged. You can see an example about how to use this in https://github.com/Haivision/srtgo/blob/master/examples/echo-receiver/main.go

[eric]

Thank you!