core: EvalDiff handling of tainted objects
core: EvalDiff handling of tainted objects

If the prior object is tainted, we behave as if it doesn't exist at all
for most of our logic here but then at the end turn it into a synthetic
replace operation going from the old object to the new object, similarly
to how we'd behave if given an argument change that "requires
replacement".

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