refactor: add alternative EVP signing method

[lrstewart]

Release Summary:

Resolved issues:

related to #5105

Description of changes:

Final required change for #5105. This adds the new non-FIPS-140-3 EVP signing method and switches all libcryptos except awslc-fips to use it.

The state of the library after this change matches the desired state described in #5105, which is:

Libcrypto	Hash method	Signing Method
openssl-1.0.2	EVP	EVP
awslc-fips	EVP	EVP-FIPS-140-3
openssl-3-fips	EVP	EVP
other	EVP	EVP

Testing:

I added s2n_evp_signing_test to the Openssl3fipsWIP build. It's nice to note that after this change, only 12/274 tests are failing for openssl-3.0-fips. A quick spot check doesn't suggest any of them are related to this change.

I also added known-value tests to s2n_evp_signing_test. That's important for a couple reasons:

1. openssl-3.0-fips can't run the comparisons with the legacy signing methods because it doesn't support the legacy signing methods.
2. I plan to remove the legacy signing methods, after which point no libcrypto will run the comparisons with the legacy signing methods
3. There are subtle mistakes that aren't caught by self-talk tests. For example, I initially wasn't setting the EVP_MD on the pkey context, which is required to get the padding right when doing RSA PKCS1. Since neither the sign nor the verify methods were setting the EVP_MD, they were both wrong in the same way.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[lrstewart]

Without this, s2n_evp_signing_test can't load the RSA-PSS certificate it needs for testing.