[wpimath] Add Eigen sparse matrix and iterative solver support (#4349)

These are useful for efficiently solving huge, but sparse systems of
equations that occur often in optimization problems.

upstream_utils/update_eigen.py

@@ -56,10 +56,16 @@ def eigen_inclusions(dp, f):
         "Core",
         "Eigenvalues",
         "Householder",
+        "IterativeLinearSolvers",
         "Jacobi",
         "LU",
+        "OrderingMethods",
         "QR",
         "SVD",
+        "SparseCholesky",
+        "SparseCore",
+        "SparseLU",
+        "SparseQR",
         "StlSupport",
         "misc",
         "plugins",