chore(auth): Add typesafe classes for handling auth tokens

[mattcreaser]

• PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:
Updates internal handling of auth tokens to wrap them in typesafe classes instead of bare strings. This makes the codebase easier to understand, drastically cuts down on the number of times the JWT strings are parsed, and makes it less likely that token content is accidentally leaked (because the masking is applied at the wrapper class level).

How did you test these changes?

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Ensure commit message has the appropriate scope (e.g fix(storage): message, feat(auth): message, chore(all): message)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

❌ Patch coverage is 53.48837% with 40 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.28%. Comparing base (288a082) to head (da58ec1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3123      +/-   ##
==========================================
+ Coverage   54.27%   54.28%   +0.01%     
==========================================
  Files        1040     1040              
  Lines       32071    32078       +7     
  Branches     4712     4721       +9     
==========================================
+ Hits        17406    17414       +8     
+ Misses      12824    12818       -6     
- Partials     1841     1846       +5     

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[tylerjroach]

Nice simplification!