Add agenda service and submit api

Signed-off-by: Asai Neko <sugar@sne.moe>

service/service_agenda/service.go

@@ -0,0 +1,11 @@
+package service_agenda
+
+type AgendaService interface {
+	Submit(*SubmitPayload) *SubmitResult
+}
+
+type AgendaServiceImpl struct{}
+
+func NewAgendaService() AgendaService {
+	return &AgendaServiceImpl{}
+}