To implement preview mode support for classes in java.base, the jimage file format needs to be modified to support alternate versions of class bytecode (and other resource entries).

This is the first of 4 PRs to migrate the core preview mode support from Valhalla to mainline. It affects the creation and reading of the jimage file, both in Java (BasicImageReader/ImageReader) and C++ (imageFile.xpp/jimage.xpp).

Of note is that the jimage tool's version number must be bumped, making it no longer possible to use the jimage tool from one JDK on a modules file of another. This was never promised to work, but has done for many years. I has a separate issue for improving the error message when version mismatch is detected.