[Enhancement] Add audio track language selection to Media Profile

[kieraneglin]

What's new?

• Adds the ability to specify an audio track in the Media Profile form (requires "Advanced Mode" to be enabled)
  • You can enter either a language code (en, de), original to download the original audio track, or default to download YouTube's preferred audio. You can also leave it blank to maintain current behaviour
  • Doesn't do anything if there is only one audio track
  • Resolves [Triage] video downloaded with wrong audio track (automatic dubbing) #482
• Adds a version string to the in-app stream elements to help bust browser caching if you re-download a file

What's changed?

N/A

What's fixed?

N/A

Any other comments?

N/A