NextRelease: lazy load DateTime

TODO: also lazy load String::Formatter, but needs an heavier
refactoring.
PkgVersion: use version::is_lax directly

This removes useless dependency on MooseX::Types::Perl for this plugin.
AutoPrereqs, PkgDist, PkgVersion: lazy load PPI

PPI is now loaded when used in the Dist::Zilla::Role::PPI.
AutoPrereqs: lazy load dependencies

By the way the single usage of List::AllUtils is replaced with
List::MoreUtils that is just enough here.
AutoVersion: one more test case: format using CLDR
AutoVersion: lazy load DateTime