feature: use the actual ngx_connection_t * in ssl_client_hello_by

[climagabriel]

Do we really need to create a fake connection here? Sure, the request struct wasn't even created yet but the conneciton does exist.
I personally need it because I need to allocate memory that will live for as long as the connection exists, not until the Lua chunk returns.

I hereby granted the copyright of the changes in this pull request
to the authors of this lua-nginx-module project.

Also, surely there must be a better way to do this.
c = ngx_ssl_get_connection(ssl_conn);
This line already does exist at the very top of ngx_http_lua_ssl_client_hello_handler().

If the real connection exists, can't we make it available in the Lua code itself?
The same way we make the fake request available by resty.core.base.get_request

[climagabriel]

I read a bit more about openresty and realized that data persisting beyond the lifetime of a request goes against the design principles of the module so I'm closing this PR.