Enable passing top-level `name` property as metadata to resources

[SteveL-MSFT]

Summary of the new feature / enhancement

Resources may need to process the user-defined name top-level property but resources only receive the object under properties. There is already a provision to pass additional context via _metadata to a resource, so this can be passed as _name (since that property is how resources inform DSC to populate the name top-level).

Proposed technical implementation details (optional)

No response

[SteveL-MSFT]

Depending on the requirements and scenario, it might be better to have a new resource type called resourceProvider which accepts and returns the full JSON at the resource level instead of passing things back and forth via metadata/canonical properties. In this case, we would also restrict resourceProvider types to allow for datetime versioning without a warning message and disallow other types from anything other than semver.