#334 Add unit tests for critical code sections [2.0]

[jamshale]

I'm sure more testing and better testing can be done but I think this is good enough for this task.
Only testing on python 3.11 now. The project is not compatible with 3.10.

I think the best testing is done in test_issue_token_service.py . It takes expected presentation payloads and assure they generate claims for valid inputs. I think this could be expanded further but it will likely come in handy as examples of how to send different payloads through the tests and will hopefully find any errors with expected functionality if a developer makes changes in the get_claims function.

Added some mock payloads which can be altered to do accurate testing and for context.

There is other testing in the acapy directory which is only somewhat useful. Still think it's nice to have for extra documentation and as a foundation for future features and proper testing.

Added a few TODO comments.

Here is the current coverage:

[esune]

Excellent work! Added a couple of notes that can likely be extended to the remaining, similar scenarios.

Regarding the assertion to check for JSON objects: we are definitely expecting to receive valid JSON,if we use json.loads() to deserialize the payload it might be unnecessary since an exception would/should be thrown there if the object is not valid JSON?