Should we change StatePreparationViaRotations to (optionally?) use SelectSwapQROM?

[wjhuggins]

I'm not sure what the best way to do this is, because there are a lot of design choices one could make and it might be hard to have sensible defaults, but I found myself wanting a version of StatePreparationViaRotations that uses SelectSwapQROM instead of QROM.

Some random thoughts about what makes this tricky:

• Dirty vs clean ancilla is application dependent and should be configurable
• In some applications one might be happy choosing the number of ancilla used automatically, but sometimes one might want to configure this
• QROM might be more efficient than the SelectSwapQROM for small data sizes and the user would obviously prefer to make the right choice each time QROM is used.

[fdmalone]

Two thoughts:

1. In general it is an open problem of how we can modify decompositions to replace bloqs which perform the same operation and have the same signature.
2. For QROM vs SelectSwap I imagine there are cases where some sensible factory method / builder could be cooked up which would perhaps decide on the optimal method to use given some considerations (ancilla count etc..), and would then potentially use 1.