Improve join the discussion feature

[lunika]

Feature Request

Is your feature request related to a problem or unsupported use case? Please describe.

In #1076 during a jitsi live we allow a participant to join the jitsi room by a submission process. The participant must ask to join and then an instructor can accept or reject the request. This feature is de facto enabled and works only the way described before. We want to improve it by allowing the instructor how this feature is enabled and its behaviour

Describe the solution you'd like

An instructor should choose to enable it or not and when it is enabled, different mode should be available:

• autojoin: When a participant join a live, he/she is automatically added to the jitsi room and the instructor can kick out any non moderator participant
• ask process: current behaviour with the submission process
• disabled: the ask button is not displayed and there is no way to join a discussion

Discovery, Documentation, Adoption, Migration Strategy

This issue can be split in several PR, one by behaviour for example.