DM-13065 adds a new low-level polynomials library to afw::math, incorporating but heavily modifying code from afw.math.ChebyshevBoundedField, meas.astrom.PolynomialTransform, and shapelet.

ChebyshevBoundedField should be reimplemented on top of the new polynomials library. This will require removing ChebyshevBoundedField's (never-used, and probably not useful) support for x and y polynomials with different orders, and it will probably involve adding a bit more functionality (integrals?) to the polynomials library as well.

This should include updating the polynomials library to utilize a more stable Clenshaw recurrence relation for some evaluation.