Add Qwen3 Audio Encoder

[eitanporat]

Description

• Add audio encoder support for qwen3

• classes such as AudioEncoder and Qwen3OmniAudioEncoder
• added the use_audio flag to the configuration.
• various audio specific flags

• added merging of audio tokens for qwen3
• added support in maxengine and maxtext_utils
• added support in decode.py

Tests

tests/check_qwen3_omni_audio_vs_reference.py

Checklist

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