annotations: add endpoint for writing graphite-like events (#9495)

* annotations: add endpoint for writing graphite-like events

* annotations: fix new line handling in tooltip

* annotations: support tags in prior to Graphite 0.10.0 format

pkg/api/api.go

@@ -292,6 +292,7 @@ func (hs *HttpServer) registerRoutes() {
 			annotationsRoute.Delete("/:annotationId", wrap(DeleteAnnotationById))
 			annotationsRoute.Put("/:annotationId", bind(dtos.UpdateAnnotationsCmd{}), wrap(UpdateAnnotation))
 			annotationsRoute.Delete("/region/:regionId", wrap(DeleteAnnotationRegion))
+			annotationsRoute.Post("/graphite", bind(dtos.PostGraphiteAnnotationsCmd{}), wrap(PostGraphiteAnnotation))
 		}, reqEditorRole)
 
 		// error test