feat: forward in-memory certs_keys in build_client_ssl_opts

[josecriane]

No description provided.

[mrrubinos]

Shouldn't we collapse these fields into something where precedence is explicitly declared?

certfile => file:filename(),
keyfile => file:filename(),
certs_keys => [map()],
cacertfile => file:filename(),
cacerts => [public_key:der_encoded()],

apart from that, LGTM

[josecriane]

As indicated in ssl documentation, https://www.erlang.org/doc/apps/ssl/ssl.html#t:common_option_legacy/0, ​​certfile, keyfile, cacertfile, and cacerts are deprecated options in favor of certs_keys.

In newer versions of nhttp_lib, we should remove legacy options.