feat(api): add /thirpartyRequests/verifications resource support

[lewisdaly]

• First pass at supporting /thirdpartyRequests/verifications
• Initial state machine setup for verifyTransaction... perhaps overkill, but seems like a good way to do async things
• Minor refactor to move state machines out of /src/model, and into /src/domain/stateMachine. Model is for database things (but I can understand the mix up)

We will need to come back to this code to implement the actual verification of an attestation, and we can take care of some other cleanup then:

• sdk-standard-components support for a proper method called putThirdpartyVerification
• auth-service changes to the payload of POST /thirdpartyRequests/verifications