`http_proto::metadata` is a heavy type (256 bytes on 64-bit machines). We need to reduce it to something similar to Boost.Beast(1) containers. Also related to: https://github.com/cppalliance/http_proto/issues/135
http_proto::metadatais a heavy type (256 bytes on 64-bit machines). We need to reduce it to something similar to Boost.Beast(1) containers.Also related to: #135