Rust Skeleton Audio Control HAL implementation.

WARNING: This is not a reference audio control HAl implementation and does not contain any actual implementation.

This folder contains a skeleton audio control HAL implementation in Rust to demonstrate how vendor may implement a Rust audio control HAL. To run this audio control HAL, include android.hardware.automotive.audiocontrol-V4-rust-service in your image.

This implementation returns StatusCode::UNKNOWN_ERROR for all operations and does not pass VTS/CTS. Vendor must replace the logic in default_audio_control_hal.rs with the actual implementation.