Crypt receipts toccata

[freshair18]

Updated the cryptographic receipts API to the new toccata sequencing commitment. Supersedes #725.

Some attempt to simplify for ease of review was made, can remove more complications if it helps

• PR is marked as draft because I believe it is currently unsafe from edge cases where pruning occurs during generation of the receipts (perhaps verification too). For this particular use case, I would personally favor failure over starving pruning, but I suspect we will tackle this issue for vProg ZK proof generation anyway (if we hadn't already), and also just replacing the panicing calls with result queries is a bit invasive with existing code.