connect the latest and greatest of build macros.  now have bootstrapping available in one word.  (and with end-to-end integrity even if you don't have mdm already available locally!)  instructions in the readme for bootstrapping without any existing mdm will continue to work, of course, but the route introduced here is easy, secure, and also a good example of how to set up bootstrapping in other projects.
upstream'd the pattern for making executable jars.