Codegen Unterminated First Line

Fixed overwrite_terragrunt and remove_terragrunt on files with no trailing newline

generate blocks using if_exists = "overwrite_terragrunt" or if_disabled = "remove_terragrunt" failed to properly handle existing files when the file at the target path had no newline after its first line, empty files included.

Terragrunt now properly handles files like this, so a file carrying the Terragrunt signature is overwritten or removed as configured, and a file without it produces the usual error naming the path Terragrunt would not touch.