Recommended gathers a list of recommended modules and versions and provides means to check if they are available. it is a thin veneer around module::runtime.

there are two major benefits over using module::runtime directly:

* self-documents recommended modules together with versions at the top
of your code, while still loading them on demand elsewhere.
* dies if a recommended module exists but fails to compile, but
doesn't die if the module is missing or the version is insufficient.
this is not something that module::runtime offers in a single
subroutine.