Fix fragment export for deploy build

[redreceipt]

Summary:

• export AUDIO_MEDIA_FIELDS from the fragment barrel
• unblock the failing deploy build for the audio embed fix already merged in Support AudioMedia in legacy embeds #267

Testing:

• npx -y yarn@1.22.22 build
• npm test -- --watch=false --runInBand VideoPlayer.test.js
• npm run lint -- --no-cache