[Feature] Add preferredAudioChannelCount for audio track selection

[KanghyunJeon]

Summary

This PR implements the feature requested in #2992.

Adds a new TrackSelectionParameters.preferredAudioChannelCount API that allows apps to prefer audio tracks with higher channel counts (e.g., 5.1, 7.1 surround) over stereo tracks, regardless of role flags (main vs alternate).

Changes

• Add preferredAudioChannelCount field to TrackSelectionParameters
• Add setPreferredAudioChannelCount(int) builder method
• Modify AudioTrackInfo.compareTo() to prioritize higher channel count when preference is set
• Reuse existing parameters and channelCount fields

Behavior

• When preferredAudioChannelCount > 0, tracks are compared by channel count before role flags
• Higher channel count tracks are preferred
• Falls back to lower channel count if higher is not supported by the renderer
• Set to 0 (default) to use original behavior based on role flags

Issue

#2992

[microkatz]

I'm going to send this for internal review now. You may see some more commits being added as I make changes in response to review feedback. Please refrain from pushing any more substantive changes as it will complicate the internal review - thanks!

[microkatz]

@KanghyunJeon

In reviewing your case further we have additional questions before we can move your PR forward. If you could please answer the questions in the connected Ticket you filed here, #2992 (comment), that would be great!

Thanks!