command/format: test for diff rendering with dynamic-typed subattrs
command/format: test for diff rendering with dynamic-typed subattrs

We use cty a little differently when a nested list block contains a
dynamically-typed attribute: it appears as a tuple value instead of a
list value so that we can retain the individual types of each element.

Here we introduce a test for that case, but doing so required also making
the runTestCases function handle types in a stricter way so that it will
produce planned values that match how Terraform Core would do it,
including the necessary late-bound type information for the
dynamically-typed attribute.

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