New Issue: [Library Stabilization] BigInteger operator methods should have better argument names

17725, "lydia-duncan", "[Library Stabilization] BigInteger operator methods should have better argument names", "2021-05-13T16:44:50Z"

All the operator arguments are named a and b except for the exponentiation and assignment operators which have appropriate names. I think these should be lhs and rhs as appropriate, and arg for unary operators.

If folks agree, I think we should update the standard module guidance to recommend this.