Add a user to a folder when joining a channel

[tailoric]

User story

1. As a user
2. I want to be added to the shared folder of a team
3. So that I can see and use the shared files relevant to my channel

Acceptance criteria

• When opening the Nextcloud Tab send a request to our backend, if the backend isn't ready yet send a dummy request or have the code for sending the request ready)
• Show the contents of the shared folder after adding the new user. (if not possible show dummy data or the current user directory)

Definition of done

• Code is reviewed and merged to main by RM (or at least a different person from the one, who has implemented it)
• The code builds without errors or if there are any - they are noted down and clearly communicated with the team
• A feature is to be implemented so that it is scalable on different devices and works consistently for the rest of the team
• The code goes successfully through the CI pipeline