Is it possible to allow `pathlib.Path` to be passed as argument to `Mesh()`?

[p479h]

As of right now, you must provide the file path to your .msh mesh using a python string. Since many users utilize python's built in pathlib.Path objects for indicating the mesh directory it would be nice to be able to pass them as arguments. I believe the solution could be added to firedrake/mesh.py _from_gmsh(filename, comm=None) as follows:

if isinstance(filename, Path):
    filename = filename.as_posix()

Or something similar.

[connorjward]

This seems like a sensible thing to support. Probably the best place to put this would be inside Mesh as your suggestion is specific to gmsh.