Change forceExtensionHostSearch strategy for easier testing

src/vs/workbench/api/common/extHostSearch.ts

@@ -105,6 +105,8 @@ export class ExtHostSearch implements ExtHostSearchShape {
 		return engine.search(progress => this._proxy.$handleTextMatch(handle, session, progress), token);
 	}
 
+	$enableExtensionHostSearch(): void { }
+
 	protected createTextSearchManager(query: ITextQuery, provider: vscode.TextSearchProvider): TextSearchManager {
 		return new TextSearchManager(query, provider, {
 			readdir: resource => Promise.resolve([]), // TODO@rob implement