Lazy loading containers (#1411)

Co-authored-by: Asier Isayas <aisayas@microsoft.com>

src/Contracts/ViewModels.ts

@@ -87,13 +87,13 @@ export interface Database extends TreeNode {
   isDatabaseExpanded: ko.Observable<boolean>;
   isDatabaseShared: ko.Computed<boolean>;
   isSampleDB?: boolean;
-
+  collectionsContinuationToken?: string;
   selectedSubnodeKind: ko.Observable<CollectionTabKind>;
 
   expandDatabase(): Promise<void>;
   collapseDatabase(): void;
 
-  loadCollections(): Promise<void>;
+  loadCollections(restart?: boolean): Promise<void>;
   findCollectionWithId(collectionId: string): Collection;
   openAddCollection(database: Database, event: MouseEvent): void;
   onSettingsClick: () => void;