[padelsbach]

Add a handful of tests for arg validation for parity with legacy

[Copilot]

🟢 Approval recommended

No active review issues are reported for the test-only expansion of cache-key argument validation.

No open issues 🎉

What changed in this PR

Expands cache-key generation argument-validation tests in the refactored client-server suite to improve parity with legacy coverage. No production code changes are included.

Changes:

• Adds RSA and ECC checks for ephemeral flags and null arguments.
• Extends Curve25519, Ed25519, and ML-DSA checks beyond ephemeral-flag rejection, including ML-DSA DMA cases.
• Registers the expanded tests and adds cleanup for any unexpectedly created cached keys.

File	Description
test-refactor/​client-server/​wh_test_crypto_rsa.c	Adds cache-key generation argument checks and registers the test.
test-refactor/​client-server/​wh_test_crypto_mldsa.c	Expands argument checks for standard and DMA cache-key APIs.
test-refactor/​client-server/​wh_test_crypto_ed25519.c	Extends ephemeral-flag checks with null-argument cases.
test-refactor/​client-server/​wh_test_crypto_ecc.c	Adds cache-key generation argument checks and registers the test.
test-refactor/​client-server/​wh_test_crypto_curve25519.c	Extends ephemeral-flag checks with null-argument cases.

_{Review effort: Balanced}