Hash checking for SRS

[ledwards2225]

Implement some kind of hash consistency checking on SRS download that confirms validity of the content. The simplest approach would be to base this on power-of-2 sized downloads but since we'd like to avoid needing to download a full dyadic SRS, a better approach might be to base it on smaller chunks so any size download can be checked.

[ledwards2225]

Closed with AztecProtocol/aztec-packages#21113