Allow `path_like` specification for filenames in batch submissions

[gvnwst]

Currently, batch submissions for modesolver (and likely FDTD) require that the path used to specify download location is given as a string. At some point in the chain, <filename>.lower() is used, which causes failing errors when the supplied filename is not a string.

To improve robustness and allow more streamlined checks for things like extensions, validity of file location, etc, it would be nice to allow path-like objects to be specified (pathlib's Path?). I typically have a data directory where simulation files are stored, separate from where my script files are located/run.

My current solution is to generate the filename and do all my checks on a Path object, then convert to string before passing to the run commands.

The functions I'm referring to for modesolver and fdtd:

tidy3d/tidy3d/web/api/mode.py

Line 147 in 78dfeff

def run_batch(

tidy3d/tidy3d/web/api/container.py

Line 191 in 78dfeff

def run(self, path: str = DEFAULT_DATA_PATH) -> SimulationDataType:

[yaugenst-flex]

Yes this is a good idea, we're tracking this internally already for better path handling in general.