fix: adding structure grid data class

Author: lachlangrose

LoopStructural/datatypes/_structured_grid.py

@@ -0,0 +1,23 @@
+from dataclasses import dataclass
+import numpy as np
+
+
+@dataclass
+class StructuredGrid:
+    origin: np.ndarray
+    maximum: np.ndarray
+    step_vector: np.ndarray
+    nsteps: np.ndarray
+    data: np.ndarray
+
+    def to_dict(self):
+        return {
+            "origin": self.origin,
+            "maximum": self.maximum,
+            "step_vector": self.step_vector,
+            "nsteps": self.nsteps,
+            "data": self.data,
+        }
+
+    def vtk(self):
+        pass