Merge similar examples in offline_inference into single basic example

[hmellor]

Motivation:

• Reduces number of unnecessary examples reducing clutter
• Basic examples are now fully configurable, making them more useful:
  • for experimentation for new users
  • as debugging tools for developers

Changes:

• Move basic.py, chat.py, classify.py, embed.py, generate.py, score.py to examples/offline_inference/basic because they were almost identical:
  • Add README to examples/offline_inference/basic walking through all the contained scripts
  • Add ArgumentParser for all EngineArgs to each of these scripts (except basic.py)
  • Add ArgumentParser for some SamplingParams for chat.py and generate.py
• Deleted examples/offline_inference/cli.py as it's no longer relevant
• Add signpost to this new example in https://docs.vllm.ai/en/latest/getting_started/examples/examples_offline_inference_index.html
• Delete and added args to recreate to README for the following examples:
  • examples/offline_inference/aqlm_example.py
  • examples/offline_inference/arctic.py
  • examples/offline_inference/basic_with_model_default_sampling.py
  • examples/offline_inference/cpu_offload.py
  • examples/offline_inference/gguf_inference.py

[github-actions]

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[DarkLight1337]

LGTM now, thanks for the cleanup

[hmellor]

Here's a link to the multi-file example that was created for posterity https://vllm--12737.org.readthedocs.build/en/12737/getting_started/examples/basic.html