[core] fix bad imports

packages/core/src/api/app/AppBuilder.tsx

@@ -19,7 +19,7 @@ import { Route, Switch, Redirect } from 'react-router-dom';
 import { AppContextProvider } from './AppContext';
 import { App } from './types';
 import BackstagePlugin from '../plugin/Plugin';
-import { FeatureFlagName } from '../plugin/Plugin/types';
+import { FeatureFlagName } from '../plugin/types';
 import {
   IconComponent,
   SystemIcons,

packages/core/src/api/app/FeatureFlags.tsx

@@ -15,7 +15,7 @@
  */
 
 // import React, { createContext, useContext, useState, FC } from 'react';
-import { FeatureFlagName } from '../plugin/Plugin/types';
+import { FeatureFlagName } from '../plugin/types';
 import { FeatureFlagsApi } from '../apis/definitions/featureFlags';
 
 // TODO: figure out where to put implementations of APIs, both inside apps