RFR: 8075617, 8075616 Create tests to check wsgen, schemagen work with multi-version jar

[Andrey Nazarov]

Hi,

I’ve added sanity checks that wsgen and schemagen tools works with 
multi-release jar files.

Review http://cr.openjdk.java.net/~anazarov/8075617/webrev.00/webrev/

JBS: https://bugs.openjdk.java.net/browse/JDK-8075616 
<https://bugs.openjdk.java.net/browse/JDK-8075616>, 
https://bugs.openjdk.java.net/browse/JDK-8075617 
<https://bugs.openjdk.java.net/browse/JDK-8075617>

—Andrey