Adding type hints to meshes

[shimwell]

Description

Added a few more type hints for the meshes.

I am looking to help get a few more features into the meshes including (SphericalMesh.from_domain and bounding boxes for Cylindrical and Spherical) and I think that adding type hints will help when implementing these changes.

Fixes # (issue)

Checklist

• I have performed a self-review of my own code
  - [ ] I have run clang-format on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
  - [ ] I have added tests that prove my fix is effective or that my feature works (if applicable)

✔️ I have run pytest on test_mesh_from_domain.py, test_mesh_from_lattice.py and test_mesh.py

[shimwell]

CI is failing with TypeError: Subscripted generics cannot be used with class and instance checks error and I think I've seen this before when trying to use PathLike as a type.

[paulromano]

Thanks @shimwell!