✨ Convert SCF operations to `jeff`

[denialhaag]

Once we start supporting SCF operations in QCO, we should add conversions from and to jeff.

[burgholzer]

How much of this is actually Jeff <-> QC and how much is Jeff <-> Standard MLIR Dialects (followed by simpler conversions for the remaining concepts from Jeff+MLIR to/from QC)?
Asked differently: can some of the changes required here be generalized to jeff-mlir?

[denialhaag]

You have a point. However, I'm not sure whether we can convert all of jeff's SCF operations to native ones, since native SCF operations generally don't support linear typing. We will definitely need some sort of conversion between qco.if and jeff.switch (or a future jeff.if). For the other ones, it might be possible to do the conversion in jeff-mlir. 🤔

Edit: In general, I'd say this depends on how SCF operations will be realized in QCO once #1396 (or a PR replacing it) is merged. If the implementation contains too many MQT-specific assumptions, I would maybe not do the conversion in jeff-mlir.

[burgholzer]

Good points. I can't quite remember if MLIR's switch statement allowed for block arguments or if similar problems as for scf.if come up there, which would necessitate something similar to qco.if.
However, I would think that many of the Jeff concepts map more-or-less naturally to scf.
At the same time, it may be easier to just get a solution working between Jeff and MQT Core without generalizing too much upfront.
Once we have a working solution, we can always pull things out to jeff-mlir if that feels reasonable.