DEVX-8994: Change default client tokens to jwt

[superchilled]

This PR adds the ability to create JWT client tokens and sets this as the default, with the option to create T1 tokens if the user specifies this. Specifically the PR:

• Updates the token creation logic to accept an optional token_type param in the generate_token method:
  • The param has two acceptable values: 'T1' and 'JWT'
    • If 'T1' is set, a T1 token is generated
    • If 'JWT' is set, or if the token_type param is ommitted, a JWT is generated
• Updates existing unit tests and add new unit tests to cover the amended and added functionality