gh-94172: urllib.request avoids deprecated check_hostname (#94193)

gh-94172: urllib.request avoids deprecated check_hostname (#94193)

The urllib.request no longer uses the deprecated check_hostname
parameter of the http.client module.

Add private http.client._create_https_context() helper to http.client,
used by urllib.request.

Remove the now redundant check on check_hostname and verify_mode in
http.client: the SSLContext.check_hostname setter already implements
the check.