App::Command::version.pm: remove need to have Moose simply to use extends.

This removes a _very serious_ number of dependencies and allows _all_
dzil commands to run without loading Moose first!

- 92 less files loaded under `dzil version`
- 20 runs of `dzil version` now take only 2 seconds instead of 6
- 'dzil version' Max RSS is now only 62800 kb instead of 119800kb