Remotestate Nil Config

Fixed crash when a root.hcl declares no remote_state block

A root.hcl that only declared locals (or otherwise omitted a remote_state block) could trigger a nil pointer dereference inside Terragrunt's remote-state initialization. Downstream tools that embed the Terragrunt config parser, such as terragrunt-ls, crashed on every such file.

A missing remote_state block now initializes an empty remote-state value instead of panicking, so parsing proceeds normally when no backend is configured.

Reported in terragrunt-ls#134.

Thanks to @SAY-5 for contributing this fix!