[11u] RFR (S) 8244031: HttpClient should have more tests for HEAD requests

[Aleksey Shipilev]

Original fix:
   https://bugs.openjdk.java.net/browse/JDK-8244031
   https://hg.openjdk.java.net/jdk/jdk/rev/a0d9d2e73ef2

The patch applies nearly exactly, but the tests need adjustments for 11u:
   - jdk.test.lib.net.SimpleSSLContext is jdk.testlibrary.SimpleSSLContext
   - @library /test/lib is @library /lib/testlibrary

ForbiddenHeadTest exposes the bug that is fixed by JDK-8244205. I'll propose it for 11u backports 
shortly.

Testing: java/net/httpclient tests

-- 
Thanks,
-Aleksey