Remove non-profile usages of DeviceUtils

[nielsvanvelzen]

We've been getting too comfortable using device identifiers to run specific code paths. This is a bad practice (just like user agent testing) and we should use feature testing instead.

Changes

• Always use downmix to stereo as default audio behavior (previously only on GTV)
• Always enable AC3 by default (previously only on everything except fire tv stick gen 1)
• Remove Android 6 check for refresh rate switching. It is disabled by default anyway so just don't use it (if you're one of our ten users running this old Android version)
• Remove some Fire TV specific behavior for initializing LibVLC

Issues

Fixes #3418

[crobibero]

Shouldn't this default to direct stream?

[nielsvanvelzen]

I've opted to enable downmixing by default as it basically just a fancy toggle for a bunch of audio codecs that a lot of devices do not support. Ideally we'd query the system whether each of them is supported or not but I'm not maintaining the old profile code, if someone else comes in to fix that I'll glady accept the PR.

[MichaelRUSF]

• Always use downmix to stereo as default audio behavior (previously only on GTV)

This will cause unnecessary transcoding as the default behavior. IMO it should be kept the way it is.

[nathansmeal]

• Always use downmix to stereo as default audio behavior (previously only on GTV)

This will cause unnecessary transcoding as the default behavior. IMO it should be kept the way it is.

AFAIK this would only require audio remuxing, which is not resource intensive as video transcoding, and even integrated CPU graphics can handle this with ease.