[php] use http_build_query for deepObject support

Created by: nadar

This fixes #11222 (closed)

The Query::build() function does not support deepObjects in query params, but the OpenAPI defintion does.

/users?id[role]=admin&id[firstName]=Alex an example from the docs.

I have replaced the Query::build() function with PHP's internal http_build_query function. I have adjust PHP default encoding to match the default encoding from Query::build() which is PHP_QUERY_RFC3986.

This change will only have an effect for the query string of the URL, encoding POST bodys is still done by Query::build().