[11u] RFR: 8213400: Support choosing group name in keytool keypair generation

[Lindenmaier, Goetz]

Hi

I would like to downport this for parity with 11.0.10-oracle.
I had to resolve the code, especially CertAndKeyGen.
There already is a downport of the CSR which I will reuse.
Please review:
http://cr.openjdk.java.net/~goetz/wr20/8213400-keytool_keypair-jdk11/01/

Orig change:
https://bugs.openjdk.java.net/browse/JDK-8213400
http://hg.openjdk.java.net/jdk/jdk/rev/ddcbc20e8c6a

Best regards,
  Goetz.