Use constants from flipper-frontend-core in flipper-ui-core

Summary: See D37139129

Reviewed By: lblasa

Differential Revision: D37238570

fbshipit-source-id: 5dbf6f179fc8957e074bad1e8f74e400644be049

desktop/flipper-frontend-core/src/index.tsx

@@ -22,3 +22,4 @@ export * from './plugins';
 export {getPluginKey} from './utils/pluginKey';
 export * from './flipperLibImplementation';
 export * from './client/FlipperServerClient';
+export {default as frontendCoreConstants} from './fb-stubs/constants';

desktop/flipper-ui-core/src/fb-stubs/constants.tsx

@@ -8,13 +8,14 @@
  */
 
 import {DeviceOS} from 'flipper-plugin';
+import {frontendCoreConstants} from 'flipper-frontend-core';
 
 export default Object.freeze({
+  ...frontendCoreConstants,
+
   // Enables the flipper data to be exported through shareabale link
   ENABLE_SHAREABLE_LINK: false,
 
-  IS_PUBLIC_BUILD: true,
-
   FEEDBACK_GROUP_LINK: 'https://github.com/facebook/flipper/issues',
 
   // Workplace Group ID's