[MLIR][Presburger] Implement vertex enumeration and chamber decomposition for...

[MLIR][Presburger] Implement vertex enumeration and chamber decomposition for polytope generating function computation. (#78987)

We implement a function to compute the generating function corresponding
to a full-dimensional parametric polytope whose tangent cones are all
unimodular.
We fix a bug in unimodGenFunc to check the absolute value of the index.
We also implement Matrix<T>::negateMatrix() and Matrix<T>::scaleRow for
convenience.