RFR: 8173372 Add tests for multi-release module jar API validator

[Andrey Nazarov]

Hi,

I’ve added tests to check what MR Jar API validator handles changes in 
module-info.class

Review: http://cr.openjdk.java.net/~anazarov/8173372/webrev.01/webrev/
JBS: https://bugs.openjdk.java.net/browse/JDK-8173372


—Andrey