feat: Updating the PyMAPDL InputSchema for HexMesh (#102)

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Open questions:

- [x] 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.
- [x] 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
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them here. Only link something if it is directly relevant. -->
- Closes https://pasteurisi.atlassian.net/browse/PD-900

#### Description of changes
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*why*. -->
- Tesseract-PyMAPDL accepts a `HexMesh` and generic BC descriptors in
its `InputSchema`

#### Testing done
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manually in stagingrepo#123", screenshots of a terminal session that
verify the changes, or any other evidence of testing the changes. -->
- See the `test.py` script.

Author: NolanBlack