Optimisations for Hash to Curve

### What is wrong?

Currently we use a 'constant' time hash to curve function.

It is possible to significantly increase speeds by removing the constant time requirements.

### How can it be fixed

The two key areas where speeds could be made are in `py_ecc/optimized_bls12_381/optimized_swu.py`:
* Returning when a solution is found in `sqrt_division_FQ2()`
* Stopping the loop in `optimized_swu_G2()` when either `success` or `success_2` is true.

Start in py_ecc/optimized_bls12_381/optimized_swu.py, focusing on sqrt_division_FQ2() and optimized_swu_G2(). Review how these functions currently handle success and success_2, then measure the hash-to-curve operations before and after the optimization. Done means the functions return earlier as described while preserving their existing curve-operation results.

Written by the indexing model from the issue text.