Unit tests for get-extensions.ts (#8470)

* root removed

* get extensions passing, 95% coverage

* removed root

* fixed root on listExtensionsChildren

api/src/cli/index.test.ts

@@ -27,7 +27,6 @@ const customCliExtension: Extension = {
 	type: 'hook',
 	entrypoint: 'index.js',
 	local: true,
-	root: true,
 };
 
 const beforeHook = jest.fn();