[Doc] Consolidate whisper and florence2 examples

[Isotr0py]

• Add encoder_decoder_multimodal.py example to instruct explicit prompt usage for multimodal encoder-decoder models
• Consolidate whisper and florence2 examples into audio_language.py and encoder_decoder_multimodal.py

[github-actions]

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[DarkLight1337]

LGTM as long as you have tested the examples yourself.