win test fix

[lefou]

• Fixed more tests for Windows
• Fix path comparissions in various test
• CI include more Windows tests
• Fixed and reworked Proguard module to make CI tests work on Windows
• Add Proguard.java9RtJar target to make runtime classes available to proguard tool.
• Scoverage: switched instance cache with classloader cache to fix for Win
• Run contrib.__.prepareOffline to avoid coursier concurrency issues
• Some version bumps in tool chain
• Cleanup

The only contrib test not working is currently Scoverage. Looks like the reader of source files does not properly closes the files resources, so that subseqent test invocations (which try to delete and rebuild a test workspace) can't remove these files on Windows (because of the specific file locking behavior).