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
• We decided that some copied code is acceptable for now.
• Are the masks, e.g., dirichlet_mask of dimension (num_nodes, n_dof)? or (num_masked_points, n_dof)? or (num_masked_points,)?
• The masks are of size 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.

[andrinr]

• The masks should be of dimension (num_masked_points,), where for jax-fem I its not actually a mask but an integer array of boundary indices where each index can be associated with a unique bc value. This is more flexible but I am open to any interface.
• Code sharing among tesseracts doesnt work that well, you can do it but then you dont get intellisense. Alternatively we could write a mini python package.