Foundation Classes - Refactor PLib_HermitJacobi implementation (#780)

Foundation Classes - Refactor PLib_HermitJacobi implementation (#780)

- Remove separate PLib_HermitJacobi.lxx and stop installing it in FILES.cmake.
- Move Hermite matrices and W coefficients into the .cxx translation unit (anonymous namespace) as constexpr/static helpers.
- Replace Handle(PLib_JacobiPolynomial) with a value member; forward WorkDegree() and NivConstr() inline to myJacobi.
- Update ToCoefficients, D0123 and related methods to use the new helper functions and value-style myJacobi API.
- Remove myH and myWCoeff members and adapt matrix/coeff access accordingly.
- Minor naming/variable adjustments for clarity (NivConstr/WorkDegree -> aNivConstr/aWorkDegree).