(PUP-2825) Refactor Ruby[type_name] type to Runtime[ruby, type_name]

This changes the type Ruby[class_name] to the more generic
Runtime[ruby, runtime_type_name] to avoid squatting on open
set of names for potential runtimes which may clash with managment
of the same runtime via a Puppet class or define.

After this change, all references to Ruby[name] should be replaced
with Runtime[ruby,name].