Add configurable RSA OAEP parameters and migrate OSSL RSA to EVP_PKEY (#833)

OAEP encryption was hardcoded to SHA-1 with an MGF1-SHA1 mask and no
label support, and PSS parameters were smuggled through an untyped
void* param / size_t paramLen pair on every AsymmetricAlgorithm method.
The void* scheme forced each backend to validate paramLen against
sizeof(RSA_PKCS_PSS_PARAMS) by hand and gave no path to carry the extra
hash, MGF, and label fields OAEP needs.

Replace the void* param / paramLen pair with a typed MechanismParam*
across the full AsymmetricAlgorithm hierarchy (RSA, DSA, ECDSA, EDDSA,
GOST, DH, ECDH, ML-DSA) for both OpenSSL and Botan. Introduce
RSAPssMechanismParam (replacing the POD RSA_PKCS_PSS_PARAMS) and a new
RSAOaepMechanismParam carrying hashAlg, mgfAlg, and an optional label.
BuildRSAOAEPParam centralises CK_RSA_PKCS_OAEP_PARAMS validation and
mapping; encrypt/decrypt, wrapKey/unwrapKey, and the OAEP key-size check
now thread the parsed parameter through to the backend. The OpenSSL RSA
backend is rewritten onto the EVP_PKEY / EVP_PKEY_CTX API (sign, verify,
encrypt, decrypt, keygen, and key import/export), dropping the
deprecated low-level RSA_* calls and supporting both OpenSSL 1.1 and 3.x
via OSSL_PARAM_BLD.

Backends type-check the parameter with isOfType() and dynamic_cast
before use, rejecting a missing or mismatched MechanismParam. OAEP label
length is capped at MAX_RSA_OAEP_LABEL_LENGTH, OAEP input size is
validated against modulus - 2*hashLen - 2, and recycle paths free the
key and algorithm on every early return. RSATests and
AsymEncryptDecryptTests are extended to cover all hash/MGF combinations,
labelled encryption, and wrong-label decryption failures.

Author: noiser7

.gitignore

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