ML-KEM Wconversion fixes

[Frauschi]

Extracted from #9732:

• fix -Wconversion warnings for ML-KEM C code
• allow ML-KEM APIs without RNG usage in case WC_NO_RNG is defined

These changes have already been reviewed and approved by @SparkiDev as part of #9732.

[Frauschi]

Jenkins retest this please

[Copilot]

Pull request overview

This PR improves ML-KEM (Kyber) build/test compatibility under stricter conversion-warning builds and RNG-less configurations by tightening type conversions, adding an ML-KEM configure variant, and adapting tests to run without WC_RNG.

Changes:

• Add --enable-mlkem coverage (including small and new no-large-code variants) to the wolfCrypt-Wconversion CI workflow.
• Update ML-KEM implementation code with explicit casts/guards to address -Wconversion-family warnings and add WC_NO_RNG compile-time handling for RNG-dependent APIs.
• Update mlkem_test() to support WC_NO_RNG by using deterministic “with random” APIs and fixed test vectors.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
wolfcrypt/test/test.c	Makes mlkem_test() work when WC_NO_RNG is set by using fixed randomness and *WithRandom APIs.
wolfcrypt/src/wc_mlkem.c	Adds WC_NO_RNG guards for RNG-dependent entry points; adds explicit casts to reduce conversion warnings.
wolfcrypt/src/wc_mlkem_poly.c	Adds explicit casts and type adjustments to address conversion warnings in polynomial/matrix code paths.
configure.ac	Extends --enable-mlkem= comma-options with no-large-code to define WOLFSSL_MLKEM_NO_LARGE_CODE.
.github/workflows/wolfCrypt-Wconversion.yml	Expands the conversion-warning CI matrix to include ML-KEM build permutations.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.

[Frauschi]

The Copilot issue is fixed now

[douzzer]

tested with

wolfssl-multi-test.sh ...
'.*all.*Wconversion.*'
'quantum-safe.*clang-tidy.*'
linuxkm-defaults-all-quantum-safe-fips-dev-clang-tidy
linuxkm-defaults-all-quantum-safe-fips-dev-noasm-clang-tidy

with --enable-mlkem added to '.*all.*Wconversion.*' scenarios.