PR summary

If the home directory cannot be created/written to, matplotlib defaults to creating a temporary folder for its caching/config. However, previously, if the home directory could not be determined, a RunTimeError was raised. Now, this pr includes code to handle the RunTimeError from Path.home() so that Matplotlib will default to using a temp directory for its cache. It will also throw a warning to describe the issue.

On Windows the following now leads to a temporary cache directory:

import os
os.environ.pop('HOMEPATH', None)
os.environ.pop('USERPROFILE', None)
import matplotlib

On Linux the following now leads to a temporary cache directory, if the user is not a part of the password database:

import os
os.environ.pop('HOME', None)
import matplotlib

closes #30449

PR checklist

• "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• [N/A] Plotting related features are demonstrated in an example
• [N/A] New Features and API Changes are noted with a directive and release note
• Documentation complies with general and docstring guidelines