Terraform now handles any actual "diffing" of resource, and the existing
Diff functions are only used to shim the schema.Provider to the new
methods. Since terraform is handling what used to be the Diff, the
provider now should not modify the diff based on RequiresNew due to it
interfering with the ignore_changes handling.
The "id" field is assumed to always exist, and must have a valid value.
Set "id" to unknown when planning new resource changes to indicate that
it will be computed.
This adds some of the required shim functions to the schema package.
While this further bloats the already huge package, adding the helpers
here was significantly less disruptive than refactoring types into
separate packages to prevent import cycles.
The majority of tests here are directly adapted from existing schema
tests to provide as many known good values to the shims as possible.
James Bardin