Re-examine synchronization usages in http and https protocol handlers

The http and https protocol handlers do blocking I/O operations while holding monitors. For the short term, this is problematic for light weight threads (a.k.a. fibers) as parking while holding a monitor will pin the underlying carrier thread.

This issue tracks exploring if the locking in HttpClient, HttpURLConnection, HttpsClient, and HttpsURLConnection can be re-examined to use j.u.c. locks around blocking I/O operations.