Change LocalClient to not explicitly store default storage directory

[jayqi]

This is my proposed alternative fix for #414. This PR is into the branch for #436.

This changes the way that LocalClient stores and accesses what the local storage directory should be. In the default case where no value for local_storage_dir is provided, accessing local storage will call the class method get_default_storage_dir to locate local storage.

This means that calling reset_default_storage_dir will instantly reset the local storage for all clients that are using the default storage, not just future new ones that are created, and not with a special case for the default client.

This feels like a more intuitive fix to me than having the special case for the default client. This means that calling reset_default_storage_dir will have the same effect as deleting all of the files inside the directory, in the sense that all instantiated clients using that storage directory get affected.

[github-actions]

🚀 Deployed on https://deploy-preview-462--gallant-agnesi-5f7bb3.netlify.app

[jayqi]

This test had failed with my new implementation, but I think the old behavior is not desirable. In the old version of this test, we reset the storage directory before instantiating p2 and writing out p1, which means p2 uses a new default local storage but p1 still uses the old default local storage.

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 93.8%. Comparing base (417fa2a) to head (729d6e7).

Files	Patch %	Lines
cloudpathlib/local/localclient.py	90.0%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##           415-glob-local    #462     +/-   ##
================================================
+ Coverage            93.6%   93.8%   +0.1%     
================================================
  Files                  23      23             
  Lines                1661    1664      +3     
================================================
+ Hits                 1556    1562      +6     
+ Misses                105     102      -3     

Files	Coverage Δ
cloudpathlib/local/localclient.py	89.4% <90.0%> (-0.7%)	⬇️

... and 2 files with indirect coverage changes

[pjbull]

Looks great, thanks!