Add playback performance metrics. Closes #1930

web/interfaces/server-status.model.ts

@@ -5,11 +5,13 @@ export interface ServerStatus {
   lastDisconnectTime?: Date;
   versionNumber?: string;
   streamTitle?: string;
+  serverTime: Date;
 }
 
 export function makeEmptyServerStatus(): ServerStatus {
   return {
     online: false,
     viewerCount: 0,
+    serverTime: new Date(),
   };
 }