[9] RFR 8170769: Provide a simple hexdump facility for binary data

[Vincent Ryan]

A hexdump facility has been available for many, many years via an unsupported class: sun.misc.HexDumpEncoder.
Although that class was always unsupported, it was still accessible. That accessibility changes with Jigsaw so I’m proposing
a very simple replacement in a new and supported class: java.util.HexDump.

Thanks.

Bug: https://bugs.openjdk.java.net/browse/JDK-8170769
Webrev: http://cr.openjdk.java.net/~vinnie/8170769/webrev.00/