Update/add/refactor Unit Commitment Constraints

[ulfmueller]

in particular for our market simulation check and adjust UC constraints.
One possible 'easy to access' source at pypsa-eur
Another source at flexABLE based on Künzel

I think it makes sense to wait for #663 and then use the optimize() function instead of lopf() in order to get the complete picture of all UC constraints.

[ulfmueller]

First running example is implemented here.
But many details remain to be done:

• integrate pypsa-eur data, addressing this dirty line
• inlcude OCGT (and in general links) into the unit commitment (see here
• address seasonal storage behavior considering the interface between pre market model and UC market model (somewhere here. How to do might be found in the master thesis by @KathiEsterl concerning snapshot clustering or NEP insights (or further literature research).

[ClaraBuettner]

* [ ]  address seasonal storage behavior considering the interface between pre market model and UC market model ([somewhere here](https://github.com/openego/eTraGo/blob/features/market-simulation/etrago/execute/market_optimization.py#L170-L172). How to do might be found in the master thesis by @KathiEsterl concerning snapshot clustering or NEP insights (or further literature research).

Do you already have a concept for this? I mean sth. like which storages should be affected by this and which data is exchanged? I could implement it (and also think about the questions I had, I just wanted to know if there is already sth. there)

[ClaraBuettner]

All the mentioned points are already included. There might be additional changes and updates in the future, but I will close this issue for now.