Organize public APIs

[hnyls2002]

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Motivation

Organize public APIs which can be directly used by from sglang import xxx

Modification

• Move core benchmarks into sglang/benchmarks
• Adjust the benchmark scripts.

Checklist

1. Ensure pre-commit pre-commit run --all-files or other linting tools are used to fix potential lint issues.
2. Confirm that modifications are covered by complete unit tests. If not, please add more unit tests for correctness.
3. Modify documentation as needed, such as docstrings or example tutorials.