Boost.Asio compatibility

[azais-corentin]

This fixes #2266.

Summary

This PR fixes the boost-asio.yml workflow which was incorrectly using standalone Asio instead of Boost.Asio, and resolves compilation errors when building with Boost.Asio.

Changes

CI workflow (boost-asio.yml):

• Disabled bundled standalone Asio (-Dglaze_USE_BUNDLED_ASIO=OFF)
• Added Boost_ROOT environment variable to properly locate Boost installation

Boost.Asio compatibility:

• Error code types: In Boost.Asio, asio::error_code is boost::system::error_code which is not implicitly convertible to std::error_code.
  Changed async callback signatures to use asio::error_code consistently.
  Use make_error_code(asio::error::eof) and make_error_code(asio::error::operation_aborted) for comparisons.
• SSL includes: Added conditional SSL header includes (<asio/ssl.hpp> or <boost/asio/ssl.hpp>) to glaze_asio.hpp
• http_client.hpp: Now includes glaze_asio.hpp instead of <asio.hpp> directly for proper abstraction

[packit-as-a-service]

One of the tests failed for ccda9c5. @admin check logs None, packit dashboard https://dashboard.packit.dev/jobs/copr/3194150 and external service dashboard https://copr.fedorainfracloud.org/coprs/build/10068660/

[packit-as-a-service]

One of the tests failed for a6a0e4b. @admin check logs None, packit dashboard https://dashboard.packit.dev/jobs/copr/3194803 and external service dashboard https://copr.fedorainfracloud.org/coprs/build/10069074/

[packit-as-a-service]

One of the tests failed for b6ac8a5. @admin check logs None, packit dashboard https://dashboard.packit.dev/jobs/copr/3197101 and external service dashboard https://copr.fedorainfracloud.org/coprs/build/10071319/

[azais-corentin]

@stephenberry could you please review this?

[stephenberry]

The PR description mentions:

I've added a to_std_error_code helper which can convert a asio::error_code to a std::error_code. There's also is_eof_error and is_operation_aborted_error.

However, these helpers don't appear in the actual diff. The implementation instead uses:

• asio::error_code consistently throughout the code
• make_error_code(asio::error::eof) and make_error_code(asio::error::operation_aborted) for comparisons

Could you update the PR description to reflect the actual changes? The current approach works fine, but the description is misleading.

[azais-corentin]

Indeed, that's a leftover from a previous attempt. I'll update.

[azais-corentin]

There, it's done.

[stephenberry]

@azais-corentin, thanks so much working this fix! It looks great! I'm merging it