Refactor classification ds

[maxjeblick]

Some (mild) refactoring of Causal Classification Problem Type:

• Removed some inference settings that are not needed for classification (all generation related settings). Fixed several parts code such that it will work with the changes.
• Extracted a separate Dataset class for Causal Classification.
• Chat Tab will not be displayed when using Causal Classification.
• Fixed a (non reported) issue and removed not needed methods in the metric classes .

[psinger]

Thanks Max and sorry for review delay.

I couldn't find any issues, lgtm!