Check signing algo in COSE attached verify

[achamayou]

Prompted by #7468, and includes #7468 after further further checks.

This change uncovered what was effectively an abuse of the ECPublicKey_OpenSSL class to cover both EC and RSA verification. The following changes have been made:

1. a generic PublicKey_OpenSSL has been added, to wrap either kind/all kinds of EVP_PKEY. This works well with t_cose, which also does.
2. ECPublicKey_OpenSSL construction now fails if the input is an RSA key, matching RSAPublicKey_OpenSSL
3. Both ECPublicKey_OpenSSL and RSAPublicKey_OpenSSL now inherit from PublicKey_OpenSSL to reduce code duplication. This may or may not be a good thing, as discussed with @maxtropets, but is an internal implementation choice that is not exposed in the public headers and can be adjusted at a later time if desired.

[Copilot]

Pull Request Overview

This PR adds algorithm verification to the COSE Sign1 verification process by checking that the algorithm specified in the COSE message header matches the algorithm supported by the verification key.

Key Changes

• Extracts the algorithm identifier from the COSE message's protected header
• Derives the expected algorithm identifier from the public key's curve type
• Validates that both algorithms match before proceeding with signature verification
• Returns early with an error if algorithms are incompatible or cannot be determined

[eddyashton]

Looks like we do the same prefix of checks in verify_detached() - can we refactor this to avoid the duplication?

[achamayou]

Ok, adding this apparently benign check has uncovered the following problems:

1. UVM endorsements are sometimes signed with RSA keys
2. That is ostensibly unsupported when constructing from a vector, whether it's DER or PEM (!!): https://github.com/microsoft/CCF/blob/main/src/crypto/openssl/cose_verifier.cpp#L129
3. And at first glance, it looks building from a crypto::Pem is subject to the same restriction: https://github.com/microsoft/CCF/blob/main/src/crypto/openssl/cose_verifier.cpp#L137
4. But it's not, really, there are no checks at all:

   CCF/src/crypto/openssl/ec_public_key.cpp

   Line 30 in 977bf24

   ECPublicKey_OpenSSL::ECPublicKey_OpenSSL(const Pem& pem)

5. This works for verification (OpenSSL handles that just fine), but obviously getting the curve from an object that thinks it's an EC Key but really holds an RSA EVP_PKEY does not work:

   CCF/src/crypto/openssl/ec_public_key.cpp

   Line 116 in 977bf24

   CurveID ECPublicKey_OpenSSL::get_curve_id() const