scheduled_task : Restore the v1 type and v1 provider to the module, make v2 provider default for v1 tasks

The scheduled_task module has thus far only shipped with a new provider, but not changed existing behavior / defaults for v1 tasks, whose type definition remains in core Puppet.

Based on some discovery, it has been determined that Puppet will always try to load module code first (types and providers) and if a module satisfies a type / provider name, the code will be loaded / cached from the module only. This means that Puppet already has a system in place that allows for overriding core types and providers with module code in a way that the original code is never even parsed.

This ends up being a critically important property for this module. This allows the existing type definition to be brought in from the Puppet core code, as well as the existing provider. Since the new provider has all the same functionality as the original provider, the old provider may then have defaultfor :operatingsystem => :windows removed, effectively neutralizing the old provider. That makes it straightforward to mark the new provider as the default and ignore the old provider when the module is present, which is the goal of this module.