Delay creation of bits in dlog_pok

[kayabaNerve]

We spend n gates creating bits for the DLog PoK, making sure they're 0/1.

Since we transcript the bits, we can create a challenge of off them. With a challenge, I believe we may not need to assert the bits are 1 or 0. We simply do challenge * bit * value on the right hand side, and weight the left hand side by challenge.

With sufficient trancripting, this should only pass as long as the correct bits were set with valid bit values.

Would reduce DLog PoK evaluation from 1.5g/p to 1g/p.