feat: add prefix hashing for mm_data

[PanZezhong1725]

Summary

Add prefix hashing support for multi-modal inputs

Motivation

Closes #issue344

Type of Change

• feat — new feature / new model
• fix — bug fix
• perf — performance improvement (no behavioral change)
• refactor — code restructuring without behavior change
• test — adding or fixing tests only
• docs — documentation only
• build / ci — build system or CI configuration
• chore — tooling, formatting, or other non-code changes
• Breaking change

Test Results of Involved Models on Supported Platforms (Please attach screenshots)

Notes for Reviewers

A new python script for sending single infer request has been added.

---

Checklist

Every contributor must verify every item below before requesting
review. Tick each box only after the check has actually been performed —
do not tick speculatively. If an item truly does not apply, replace the
checkbox with N/A and briefly explain why in an inline comment.

Title, Branch, and Commits

• PR title follows Conventional Commits (e.g. feat(nvidia): …, fix(cuda/gemm): …).
• Branch name follows <type>/xxx-yyyy-zzzz where <type> matches the PR title's Conventional Commits type and words are joined with hyphens (see CONTRIBUTING.md §Branches).
• Each commit message follows Conventional Commits.
• Small PR is a single squashable commit; or, for a large PR, every commit is meaningful, well-formed, and independently reviewable (see CONTRIBUTING.md §Pull Requests).
• No stray merge commits from main — the branch is rebased cleanly on top of the current main.
• No fixup! / squash! / wip commits remain.
• Existing PR/branch/commit that followed the legacy issue format.

Scope and Design

• Changes are minimal — nothing unrelated to the stated motivation was added (CONTRIBUTING.md §Code/General).
• No dead code, commented-out blocks, debug prints, printf/std::cout/print(...) left behind, or TODO without an owner and issue link.
• No unrelated formatting churn that would obscure the diff.
• Public API changes (if any) are intentional, documented, and reflected in affected callers/tests.

General Code Hygiene (applies to all languages)

• The code is self-explanatory; comments were added only where the why is non-obvious (CONTRIBUTING.md §Code/General).
• Every modified or added file ends with a single trailing newline (CONTRIBUTING.md §Code/General).
• No trailing whitespace, tab/space mixing, or stray BOMs.
• Identifiers in comments and error messages are wrapped in backticks (e.g. the `seqlens_k` tensor) (CONTRIBUTING.md §Code/General).
• All comments and error messages are in English (CONTRIBUTING.md §Code/General).
• Comments and error messages are complete sentences — capitalized first letter, terminal punctuation — unless the language/framework convention says otherwise (CONTRIBUTING.md §Code/General; §Python).

C++ Specific (if C++ files changed)

• Code follows the Google C++ Style Guide strictly.
• Error and warning message wording follows the LLVM Coding Standards (CONTRIBUTING.md §C++).
• Constructor initializer list order matches member declaration order (CONTRIBUTING.md §C++).
• No raw new/delete; RAII / smart pointers / existing allocators are used.
• Changed files are formatted by scripts/format.py.
• No changes/reference to csrc/models/llama_legacy/.

Python Specific (if Python files changed)

• Code is PEP 8 compliant.
• Comments are complete English sentences, starting with a capital letter and ending with punctuation; Markdown backticks are used for code references (CONTRIBUTING.md §Python).
• Docstrings (if any) follow PEP 257 (CONTRIBUTING.md §Python).
• Changed files are formatted by scripts/format.py.
• No changes/reference to python/infinilm/auto_config.py.

Testing

• For any platform that could not be tested, an explicit reason is given in the table and a reviewer with access has been tagged.
• Passed single request test (examples/test_infer.py), or specify the reason for skipping.
• Passed offline performance test (examples/bench.py), or specify the reason for skipping.
• Passed sanity test (test/bench/test_benchmark.py), or specify the reason for skipping.
• Passed service test (python/infinilm/server/inference_server.py + scripts/test_perf.py), or specify the reason for skipping.

Build, CI, and Tooling

• The project builds cleanly from a fresh directory on at least one affected platform.

Documentation

• README.md, CONTRIBUTING.md, or inline docs updated when behavior, build flags, or developer workflow changed.
• Any user-visible breaking change is called out explicitly under "Motivation" and in the commit/PR title with a ! or BREAKING CHANGE: footer.

Security and Safety

• No secrets, access tokens, internal URLs, customer data, or personal hardware identifiers have been committed.
• Third-party code is license-compatible and attributed.
• No unsafe pointer arithmetic, uninitialized reads, or missing bounds checks were introduced.

[wooway777]

注释和log信息都需要用英文