Re-engineer testcases and results handling

[mbuechse]

resolves #951

[mbuechse]

@garloff @fkr @depressiveRobot
This is now ready for review. I have taken the liberty to deploy it to the server, so you can already see how it works (or doesn't).

Benefits:

• Every single file touched here is becoming smaller. In total, we're losing almost 300 lines
• We are also losing obscure concepts, such as selector expressions.
• Everyone is going to save a click each time they want to jump from the details page into the report. The detour via uuid is gone at long last!
• This is going to pave the way for future improvements, such as [Feature Request] Restructure CM details page #1055

Please give it a chance.

[garloff]

Nice work 👍

[mbuechse]

@garloff Thanks! It's one step in a long sequence of steps, I'm afraid, but an important one. Many things are still suboptimal, but I hope we can address them later.