feat: Updating the PyMAPDL InputSchema for HexMesh

[NolanBlack]

Open questions:

• Can we standardize the MeshFactory, BCFactory, HexMesh, etc. classes? They are all shared by multiple tesseracts at this point
• Are the masks, e.g., dirichlet_mask of dimension (num_nodes, n_dof)? or (num_masked_points, n_dof)? or (num_masked_points,)?

Relevant issue or PR

• Closes https://pasteurisi.atlassian.net/browse/PD-900

Description of changes

• Tesseract-PyMAPDL accepts a HexMesh and generic BC descriptors in its InputSchema

Testing done

• See the test.py script.