[Feature]: Better handle the Globus token file

[forsyth2]

Summary

Objectives:

• Allow the storage of multiple tokens in a token file.
• Allow the user to specify a token file.

Issue resolution:

• Closes [Feature]: Better handle the Globus token file #398

Select one: This pull request is...

• a bug fix: increment the patch version
• a small improvement: increment the minor version
• a new feature: increment the minor version
• an incompatible (non-backwards compatible) API change: increment the major version

Small Change

• To merge, I will use "Squash and merge". That is, this change should be a single commit.
• Logic: I have visually inspected the entire pull request myself.
• Pre-commit checks: All the pre-commits checks have passed.

[forsyth2]

Remaining TODO:

• Specify token file with parameter rather than environment variable.
• Update update.py, and extract.py accordingly, if needed.
• Visually inspect code changes (changes suggested by Claude).
• Run updated test.