Query for presentation event log

[babisRoutis]

This PR adds a new option to the VerifierAPI that would allow the Verifier to obtain a list of events, the event log, for a presentation.

• [x] Introduce a sealed hierarchy PresentationEvent, to represent notable events
• [x] Allow the use cases, to publish such events
• [x] Add a new option to VerifierAPI to allow the retrieval of the event log
• [x] Add an in memory repo to store such events
• [x] Add to OpenAPI the new endpoint
• [x] Consider adding unhappy path events
• [x] Introduce a timer to remove those events from the repo

Closes #178

[babisRoutis]

@dzarras I think that it is ready. Please check the OpenAPI addition

[dzarras]

@babisRoutis Besides the two points above, the PR is ready for merging.