Fix problems fetching performance and memory issues (#724)

* request only alert message when invoking alert.get

* fetch problem alerts on demand

* problems panel: refactor

src/panel-triggers/types.ts

@@ -162,6 +162,7 @@ export interface ZBXAcknowledge {
 }
 
 export interface ZBXAlert {
+  eventid: string;
   clock: string;
   message: string;
   error: string;