Consider switching from the Apache HTTP client to the JDK HttpClient

Currently, Elytron makes use of the Apache HTTP Client (i.e., org.apache.http.client.HttpClient). Now that JDK 11 and higher includes HttpClient APIs, we should consider switching to that instead.

We could then look at customizations related to TLS and add the HTTP mechanisms Elytron supports as well.

Zulip discussion: https://wildfly.zulipchat.com/#narrow/stream/173102-wildfly-elytron/topic/SSLSocketFactory.20in.20SSLContext