Explicitly sort annotated package and class names before adding them to MetadataSources to achieve platform independent repeatable builds

[afedotov]

Files.walkFileTree() has unpredictable iteration order, especially on different platforms like macOS and Windows. Also generated DDL script content depends on order in witch classes are added to metadata with MetadataSources.addAnnotatedClassName(). As a consequence, running same build on different platforms results in differing DDL scripts (in terms of table / column order). To ensure repeatable builds just explicitly sort package and class names before adding them to metadata.

[jkubrynski]

Thanks for the contribution!