Load default openssl config when possible

[simo5]

Description

Changes kryoptic (in non-fips builds) to try to load the default openssl configuration on the custom context.
Because the configuration file could be missing for "legitimate" reasons, we do not treat as fatal the failure to load the default configuration.

Fixes #319

Checklist

• Test suite already has enough coverage for this change
• Rustdoc string were added or updated
• CHANGELOG and/or other documentation added or updated
• This is not a code change

Reviewer's checklist:

• Any issues marked for closing are fully addressed
• There is a test suite reasonably covering new functionality or modifications
• This feature/change has adequate documentation added
• A changelog entry is added if the change is significant
• Code conform to coding style that today cannot yet be enforced via the check style test
• Commits have short titles and sensible text
• Doc string are properly updated

[Jakuje]

the pkcs11-provider integration test failure is a recursion when we try to load the pkcs11 provider into the kryoptic's openssl context?

[Jakuje]

the pkcs11-provider integration test failure is a recursion when we try to load the pkcs11 provider into the kryoptic's openssl context?

In that case, I think doing this in the kryoptic pkcs11 module is not that great idea :) But for any other users of ossl bindings, ye, this looks good to me.

[simo5]

the pkcs11-provider integration test failure is a recursion when we try to load the pkcs11 provider into the kryoptic's openssl context?

In that case, I think doing this in the kryoptic pkcs11 module is not that great idea :) But for any other users of ossl bindings, ye, this looks good to me.

This is why I had created a new context an not loaded the default config in the first place ... sounds like we should revert this commit and rethink the strategy.

There are two reasons we wanted to load the default config:

1. crypto-policies
2. loading the FIPS provider when kryoptic is build with dynamic openssl bindings

Perhaps we should create a custom configuration file for kryoptic that loads just crypto-policies snippets but only the default provider. That would take care of both 1 and 2 w/o the risk of pulling in other providers that may break it?

[Jakuje]

That makes it much more complicated, but likely only reasonable solution.

[simo5]

/gemini review

[gemini-code-assist]

Code Review

This pull request modifies the OsslContext to automatically load the default OpenSSL configuration file and adds support for managing OpenSSL providers. It introduces a providers vector to track loaded modules, a method to load the legacy provider, and logic to unload providers when the context is dropped. The review feedback highlights a typo in the changelog and suggests using the trace_ossl! macro to improve error logging when provider loading fails.