Resolve "Waiting room should refresh when the slot starts (or when the room is claimed)"

What does this MR do?

Automatically reloads the guest page when the patient has entered the call. On the backend, this involved splitting up the room creation process into a prepare step (room is created, but still closed) and an activation step (patient has entered and set up the room). The guest checks for this every 15s.

Closes #108 (closed)

Does this MR meet the acceptance criteria?

• I have added tests to validate the new functionality.
• I have updated the documentation accordingly.
• I have added translations for all new client-side text.