QROAM stub

[fdmalone]

In the interim before we have a bone fide qroam bloq with decomposition (xref #368), it's important to capture the costs in a better way that what is in https://github.com/quantumlib/Qualtran/blob/main/qualtran/bloqs/chemistry/black_boxes.py#L73, i.e. the bloq has a proper signature and can be used with existing chemistry bloqs in their decompositions. This would "fix" our current costs which rely on SelectSwapQROM and results a ~ 2x discrepancy from the literature values.

TODO:

• delete / replace the QROAM bloq in black_boxes. The downside to this is I would need to fake some input date for some bloqs which don't accept hamiltonian coefficients yet.

[fdmalone]

I'll close this in favor of @tanujkhattar suggestion which is:

1. Add clean ancilla version of SelectSwapQROM which will fix the factor of 2 cost difference.
2. Add a QROM adjoint bloq which uses table lookups for QROM and SelectSwapQROM^ (xref: Qrom adj #950).

SelectSwapQROM.adjoint() would then return QROM^