feat: generate and validate nonces in authorization requests

[coplat]

Description of change

Introduces end-to-end handling of nonces within the authorization flow. Previously, the API layer did not natively generate nonces. This update adds the logic to generate a secure nonce at the start of the flow and enforces validation of the returned nonce within the authorization response to prevent replay attacks.

Links to any relevant issues

• Blocked by fix: retain Presentation layer during decoding to allow nonce extraction openid4vc#115

How the change has been tested

Existing aggregate tests have been updated to include the nonce parameter. An additional test has been added to test instances where the wrong nonce is returned.

Definition of Done checklist

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• 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
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