feat(ocpp2.0): implement Authorize request, fix double TransactionEvent(Started)

feat(ocpp2.0): implement Authorize request, fix double TransactionEvent(Started)

OCPP20AuthAdapter.authorizeRemote() was incorrectly sending a
TransactionEvent(Started) as a proxy for authorization, causing a
duplicate Started event when ATG subsequently called
startTransactionOnConnector(). Implement the proper OCPP 2.0.1
Authorize request/response flow, harmonizing the auth+start sequence
with OCPP 1.6: Authorize first, then TransactionEvent(Started).