[contrib] Add Qwen2-Audio-7B NeuronX port

[lutfanm-aws]

Summary

• Adds NeuronX Distributed Inference implementation of Qwen/Qwen2-Audio-7B
• Multimodal audio-to-text model (~8.2B params): audio encoder + Qwen2 7B language model
• Both audio encoder and language model run entirely on Neuron hardware
• Validated with speech transcription, audio captioning, and text-only generation

Model Details

• Architecture: Multimodal encoder-decoder (Whisper-style audio encoder + Qwen2 decoder)
• Parameters: ~8.2B (audio encoder ~600M + LM ~7.6B)
• TP Degree: 2
• Precision: BF16

Validation

• Speech transcription: exact match ✅
• Audio captioning: correct caption ✅
• Text-only generation: correct response ✅
• Configuration: TP=2, batch_size=1, seq_len=1024

Performance

• Token generation: 15-16 tok/s on trn1.32xlarge (TP=2)
• Audio encoding: ~60ms for 3-4s audio

Files

• contrib/models/Qwen2-Audio-7B/src/modeling_qwen2_audio.py — Model implementation
• contrib/models/Qwen2-Audio-7B/src/configuration_qwen2_audio.py — Config classes
• contrib/models/Qwen2-Audio-7B/test/ — Integration tests
• contrib/models/Qwen2-Audio-7B/README.md — Documentation