WL#1793: SHOW COLLATION: Add Java and Windows Encoding Names to output

Affects: Server-7.1   —   Status: Un-Assigned   —   Priority: Low

Currently, non-libmysql-based clients (or remote clients) don't have access to
updated charsets/Index.xml data that tells the clients how to map charset #'s to
charset names.

JDBC and .Net clients have to currently hard-code this mapping because the names
we use inside the server for encodings and collations mean nothing to the Java
and .Net runtimes, and thus can get out of date (and don't allow custom mappings).

It would be handy if Index.xml had entries for Java and Windows/.Net encoding
names, which could be exposed via something like 'SHOW FULL COLLATION',
therefore in effect 'future-proofing' these clients from charset naming changes
and additions.