fix(platform): vhd should reset search after closing dialog (#12407)

Author: mikerodonnell89

libs/platform/value-help-dialog/value-help-dialog/value-help-dialog.component.spec.ts

@@ -135,4 +135,13 @@ describe('PlatformValueHelpDialogComponent', () => {
         testComponent.vhdComponent.onSelect(testComponent.data.slice(0, 3));
         expect(testComponent.vhdComponent.valueChange.emit).toHaveBeenCalled();
     });
+
+    it('should handle dialog close', async () => {
+        testComponent.vhdComponent.open();
+        testComponent.vhdComponent._mainSearch = 'test';
+        if (testComponent.vhdComponent.activeDialog) {
+            testComponent.vhdComponent.activeDialog.close();
+        }
+        expect(testComponent.vhdComponent._mainSearch).toBe('');
+    });
 });

libs/platform/value-help-dialog/value-help-dialog/value-help-dialog.component.ts

@@ -737,6 +737,7 @@ export class PlatformValueHelpDialogComponent<T = any> extends VhdComponent impl
     /** @hidden */
     private _resetState(): void {
         this._resetSourceStream();
+        this._mainSearch = '';
         this.activeDialog = undefined;
     }