ABI: Support power of two unsigned integers > 64 bits

[michaeldiamant]

Problem

https://github.com/algorandfoundation/ARCs/blob/main/ARCs/arc-0004.md defines support for unsigned integers up to 512 bits. As of #154, PyTeal offers 64 bit support.

To help close PyTeal's ABI support gap, the ticket requests supporting N bits where 64 < N <= 512 subject to ARC-0004 constraints.

Solution

TBD - Suggest reviewing existing repo conventions when picking up the work.

Dependencies

Optional: Consider if #252 ought to be picked up in tandem.

Urgency

TBD