Guard old non-ctx ML-DSA API by default

[Frauschi]

Summary

This PR guards the legacy non-context ML-DSA API behind WOLFSSL_DILITHIUM_NO_CTX and makes context-aware APIs the default path.

What changed

• Added no-ctx as a valid --enable-dilithium option in configure.ac to explicitly enable legacy no-context APIs.
• Wrapped legacy no-context C APIs and ML-DSA compatibility aliases in #ifdef WOLFSSL_DILITHIUM_NO_CTX in wolfssl/wolfcrypt/dilithium.h and wolfcrypt/src/dilithium.c.
• Kept draft behavior compatible by auto-defining WOLFSSL_DILITHIUM_NO_CTX when WOLFSSL_DILITHIUM_FIPS204_DRAFT is enabled.
• Updated internal consumers to FIPS 204-style context APIs (ctx=NULL, ctxLen=0):
  • wolfcrypt/test/test.c
  • wolfcrypt/benchmark/benchmark.c
  • Rust wrapper (build.rs, src/dilithium.rs)
• Adjusted tests:
  • Legacy sign/verify tests now require WOLFSSL_DILITHIUM_NO_CTX.
  • Added/registered context KAT tests (test_wc_dilithium_sign_ctx_kats, test_wc_dilithium_verify_ctx_kats).