Add handling of getting + using tokens from IdP for authN

[marshallmcdonnell]

Need to work on how to:

• Get tokens from an identity provider for OIDC using the python client
• How to properly handle the tokens on the User's machine (where to put them? what file permissions?)
• Send the tokens with API requests to the catalog

[marshallmcdonnell]

@SmithRWORNL made a good suggestion for the handling of the tokens initially but just hold in memory for now (not worry about handling the token between processes)

This will get us far enough along to get single-process, tokenized API calls working.