Programming Exercises: Add "online IDE" button to Exercise Details

[iyannsch]

Is your feature request related to a problem?

The currently existing online code editor in Artemis is a great tool for beginners to jump into programming exercises. However, its functionality is limited for more advanced use cases. In my master's thesis, we implement the online IDE Theia as an alternative way to interact with the Artemis exercise workflow. Student do not have to set up an IDE locally anymore, saving them time and the struggle to configure it to fit their numerous courses. Currently, there is no entry point (or jump-off point) for students to start their Theia Instance from Artemis.

Describe the solution you'd like

Add a new Spring Profile named Theia that toggles all features contained in this but also feature features related to this topic. This allows to isolate all "online IDE" related functionality to a test server for now. As not all institutes necessarily want to use Theia, the existing system should stay entirely intact.

Add a new button to programming exercises after having started it for opening Theia. I suggest adding the button on the right side of Open repository which leads to the current online code editor.

Add new Theia-Config file in Artemis configs for setting the Theia Base-URL.

Describe alternatives you've considered

We could also start the online IDE by default (e.g., in an iFrame) or use the existing Open repository button for linking to Theia. I think it makes more sense to get a functional system running first, though. In future, I'd like to discuss any user experience aspects of the required entry point.

Additional context

This is a sub-issue of the feature proposed in #8602