JWKS caching via lestrrat-go/jwx, signature/iss/aud/exp validation, and
a single gRPC interceptor that grpc-gateway's forwarded headers make
work identically for REST callers.
Adds queue_service.proto (SendMessage, SendMessageBatch, ReceiveMessage,
DeleteMessage, DeleteMessageBatch, ChangeMessageVisibility(Batch)) with
grpc-gateway REST annotations, plus the generated Go server/client and
gateway stubs.
riotpiaole