Pass record-specific token to country config when registering a event

[naftis]

Currently, the registrar's token is passed to country-config, so it can call core back to confirm or reject the registration. We need to amend this so, that we create a record-specific token using the token exchange endpoint.

This enables us to send the record-specific token to MOSIP, so the access is limited if the token is leaked and we can control the tokens time to live.

Dev tasks

• [x] initiateRegistration calls country-config for the event-registration endpoint. Before calling the endpoint, call auth-services token exchange endpoint to exchange the token, and use that token to call country config

[naftis]

@onnee04 the end-to-end tests are sufficient to QA this ticket