terraform: new apply resource node supports data sources
terraform: new apply resource node supports data sources

This enables the new apply graph's resource node to apply data sources.
Data sources appear to only be tested for "refresh" which is likely
where they're set but they've also been implemented (not my code, not
trying to edit code) within the "apply" operation as well.

This adds an apply test to ensure data sources work, and then modifies
the new apply node to support data sources.

hashicorp/terraform-plugin-sdk,hashicorp/terraform-plugin-sdk