Stack Dependencies Autoinclude Hcl Tooling

stack-dependencies: HCL tooling now handles autoinclude

Two tooling gaps around the experimental autoinclude block are closed:

• hcl validate now validates autoinclude blocks. With the stack-dependencies experiment enabled, validating a terragrunt.stack.hcl that declares autoinclude runs the same strict checks as terragrunt stack generate. A malformed block (for example, a locals block inside autoinclude) is now reported at validation time instead of passing hcl validate and only failing later during generation. Without the experiment, validation behavior is unchanged.

• read_terragrunt_config() can read stack-level autoinclude files. Reading a generated terragrunt.autoinclude.stack.hcl previously failed because the file was decoded as a unit configuration, which rejects its unit and stack blocks. With the experiment enabled, the file is now decoded as the stack-file fragment it is, returning its unit and stack blocks the same way reading a terragrunt.stack.hcl does. Unit-level terragrunt.autoinclude.hcl files already read correctly and continue to do so.