Support transports other than HTTP(S) (First approach)

[veigaribo]

This implements a solution for the issue #7789.

Basically I created an on_agent_ready method for InputChannels, that is registered to run once the server has started.

The ideia is that, by using this method, people will be able to stablish connections to things that work in some way other than HTTP(S), because the on_new_message will be available to run immediately (in contrast to blueprint, which runs at a point where one cannot call the on_new_message callback yet).

Two approaches were suggested in the aforementioned issue, and this is the implementation of the first one.

An example InputChannel that utilizes this feature is available at https://github.com/Veigaribo/example-rasa-amqp-connector/blob/master/connectors/amqp.py

Questions

• Are there any tests I need to change / add? I wasn't able to find any tests for the channel module in specific;

Status:

• [ ] added some tests for the functionality
• [ ] updated the documentation
• [ ] updated the changelog (please check changelog for instructions)
• [ ] reformat files using black (please check Readme for instructions)

[sara-tagger]

Thanks for opening a draft pull request 🚀If you have any questions, you can direct them to @rctatman ✨

[stale[bot]]

This PR has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.