RFR 8180569: Refactor sun/security/krb5/ shell tests to plain java tests

[Weijun Wang]

Please take a review at

   https://cr.openjdk.java.net/~weijun/8180569/webrev.00

I've combined ktarg.sh, ktmissing.sh, and ktzero.sh into KtabZero.java.

rcache_usemd5.sh is renamed to ReplayCacheTestProcWithMD5.java. The test has no content and is only used to launch another test. I don't want to combine them because I want different working directory.

runNameEquals.sh is left as a shell test. It calls quite some *nix commands and is better to stay unchanged.

Thanks,
Max