fix(#587): noise problems when using Android microphone

[rollersteaam]

Summary

• Enables noise suppression in AudioProcessing::Config so it is actually applied when processing audio from the Android microphone
• Adds audio processing pipeline in UnityAudioTrackSource to route audio frames through WebRTC's built-in Audio Processing Module (APM)
• Disables high-pass filter to avoid over-filtering low-frequency voice content on Android

Motivation

Fixes #587. Android microphones produce extremely noisy audio due to hardware characteristics. While WebRTC's APM supports noise suppression, it was not being applied because audio frames were not being routed through the APM pipeline in the plugin's C++ layer.

Test plan

• Build the plugin with the Android target and test microphone audio capture
• Verify noise suppression is audibly effective on an Android device
• Confirm no regression in audio quality on other platforms (iOS, desktop)

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