[JDK-9] RFR: 8048610 Implement regression tests for bug fixes in JCE

[zaiyao liu]

Hi all,

Please help to review those 2 new tests to verify following 2 JDK bug 
fixes in JCE:

- JDK-4686632: InvalidKeyException.getMessage() returns null
- JDK-4901658: Can not produce a string from key's encoded byte[] 
consistently

JDK issue: https://bugs.openjdk.java.net/browse/JDK-8048610
Webrev: http://cr.openjdk.java.net/~zailiu/8048610/webrev/

Thanks

Kevin