JarFile and MRJAR tests should use the JDK specific Version API

Currently JarFile and MRJAR tests use sun.misc.Version to retrieve the major runtime version. They should be
updated to use the new JDK specific Version API.

Note: There is an issue, JDK-8144062, to revisit the JDK specific Version API to determine if it should be moved, or
even standardized. The changes being proposed here may need to be updated, in a trivial way, in the future,
but this issue is intending to break the dependency on sun.misc.Version so that JDK-8150162 can make progress.
Additionally, the future refactoring will most likely be trivial.