Play HLS with Exoplayer on Android

[uvjustin]

See also: home-assistant/core#38125 & home-assistant/android/pull/739
H.265 videos are not supported through Chromium or Webview on Android. We can work around this for Android by using Exoplayer which supports H.265 if the codecs are available on the device. This PR uses the externalApp interface to test whether Exoplayer is available from the config and uses the interface to send the requests to Exoplayer if available. I will open another PR on the Mobile App repository to implement the Exoplayer interface on the Android side.

Proposed change

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

[bramkragten]

I'm not familiar with ExoPlayer and the Android part, so can't really judge it, but not sure this is something we want to support...

[uvjustin]

I'm not familiar with ExoPlayer and the Android part, so can't really judge it, but not sure this is something we want to support...

I think this is the easiest way to get H.265 playing in app. Otherwise Android users are SOL if they want to use H.265. If the client doesn't support it (another platform, browser, or app) it just reverts to the usual functionality. Adding this might seem excessive for just one additional bit of functionality on one component, but I think it's a pretty important function as many cameras are moving to H.265 and the codec affords a significant bandwidth reduction over H.264.
Maybe some others can weigh in on this? To try it out you have to use this PR together with the PR on the android app.

[balloob]

2 final comments. Rest looks good.