Merge branch 'restructure' into project/restlike

cmd/single.go

e2e/e2eMessageBuffer_test.go

e2e/utils_test.go

single/listener_test.go

single/message/requestPart_test.go

single/message/request_test.go

single/message/responsePart_test.go

single/receivedRequest.go

single/receivedRequest_test.go