Shared logic for Dist::Zilla-related bootstrap things

 Dist::Zilla::Role::Bootstrap is a Dist::Zilla role that aims to be
 consumed by plugins that want to perform some very early bootstrap
 operation that may affect the loading environment of successive
 plugins, especially with regards to plugins that may wish to build
 with themselves, either by consuming the source tree itself, or by
 consuming a previous built iteration.