feat: implement JWT utility functions

[nanderstabel]

Description of change

Adds utility functions for JWT handling.

Links to any relevant issues

n/a

How the change has been tested

Added get_unverified_jwt_claims_successfully_gets_claims unit test

Definition of Done checklist

Add an x to the boxes that are relevant to your changes.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes