Fixes #5061: create generic method to check http status

After a lot of thinking, I have finally understood what bothers me about this name. It is unclear what it does: it looks like a simple HTTP check, Nagios-style.

I know we already defined a naming convention, but I would like to change it. We decided that all methods would be named http_get_* and http_post_*, and be wrappers around central http_* bundles. I would like to change that last category to be http_request_* instead.

So this method would be renamed http_request_check_status_headers. Is that OK for you? If so, can you rename it, and adapt the @name tag above to be "HTTP request check status (with headers)"?