Remove the uber template

This has been moved to playdoh itself

 - added --dirname feature
 - refactored the Template and entry point

cc @sh1mmer @kumikoda
@dfellis but I'll bump the major ;)

I already migrated the templates, the source of truth is no longer here.

I basically want to turn `ngen` into a scaffolding tool with no default opinions about what it's scaffolding.