Introduce Unit tests for MKey PSA refval-id and UUID

[yogeshbdeshpande]

Introduce Unit tests for MKey PSA refval-id and UUID
Currently Marshal/UnMarshal, JSON/CBOR Negative tests and also specific Positive unit tests are missing from the CoRIM Repository!

This issue tracks the lack of tests!

[ravjot07]

@yogeshbdeshpande @thomas-fossati Hi there! I noticed that the current test file for UUID covers basic scenarios for UUID and TaggedUUID, but it could benefit from additional coverage. For example, we could add tests for invalid inputs, RFC4122 compliance checks, and round-trip serialization with both valid and invalid data. This would help ensure that the code is more robust and error-resistant. Would it be okay if I work on adding these improvements and open a pull request?