todo list of make the verifier production usable on aptos

[nanne007]

Although we had verified the correctness of the verifier. Still many problems to be resolved to make it usable on aptos mainnet.

• [ ] aptos limit on elments mem usage during a session. see #47
• [ ] the problem of different serialization of bn254 curve point between halo2 and arkworks.
• [ ] to solve the problem above, we have to calculate Y based on X which needs a sqrt function on base field. That's missing on atpos. we implemented it with a pow(u256), https://github.com/zkmove/halo2-verifier.move/blob/ac00bde56f0608031cdb19867706ea79406c5943/sources/bn254_utils.move#L55 which has very low efficiency.
• [ ] currently, we implement pow function with pure move, https://github.com/zkmove/halo2-verifier.move/blob/ac00bde56f0608031cdb19867706ea79406c5943/sources/bn254_utils.move#L64 which can consume many gas when the power is big. should be optimized.
• [ ] currently, we cannot store a crypto element in state. Had to store them in serialized form. It's inconvenient for developers.