delegates interpolation of MPRS coefficients to a MA05 subclass, which uses the native coefficients for better interpolation, to compute the reference GM to which BA08 site scaling is applied. this works but needs to be cleaned up.

add BA08 site scaling term following AM09 implementation. adjust coefficient file (and tests) accordingly

MA05 implementation fixes. fix interpolated GMM set up - add missing MPRS IMTs to coefficient file with placeholders, and update (partially validated) test results

- coefficients a1, cAk, and cCasc have 15 decimal places in EQS xlsx file, rounded to 6 decimal places
- coeffs a28, a29, a31, a32, a33, a34, a35, a36, and a37 had one or more values truncated, so additional decimal places are now included
- coeff a16 is not used in nshmp-lib code (Taiwan-specific) and has been removed
- coeffs e0, e1, and e2 are not referenced in the code or the EQS paper and have been removed