OnlineIDE: Integrate Theia in the Artemis exercise workflow

[iyannsch]

Is your feature request related to a problem?

tba

Describe the solution you'd like

Integrate Theia in the Artemis exercise workflow

Describe alternatives you've considered

tba

Additional context

This issue relates to #8602

As a student, I want to access a configured online IDE to work on my exercises

As a user, I want to access a fitting Theia Workspace from my regular exercise workflow.

As a user, I do not want to re-authenticate for Theia access.

As a user, I want to return to Artemis quickly without entering the URL again.