[For reference] Use new CS api endpoint

[toger5]

This is using the new cs api and widget api based endpoints.
Part of: https://github.com/orgs/element-hq/projects/139/views/1?pane=issue&itemId=5233491139&issue=element-hq%7Cvoip-internal%7C684

It is of course entangled with the delayed work happening here: #4209

For now I will open it as reference what needs to change to allow using the new endpoints.

• The js-sdk work now has been merged so the custom js-sdk version is not needed anymore
• This needs to be implemented with the correct checks. If the widget driver does not support those actions it will result in an error and we should try agian with the direct calls to the jwt service.