Get Original Terragrunt Dir

get_original_terragrunt_dir() now resolves correctly during dependency parsing

A regression introduced in v1.0.0-rc3 caused get_original_terragrunt_dir() to return the dependent directory instead of the dependency's directory when parsing dependency configurations from a unit.

This broke configurations where a dependency's read_terragrunt_config() chain relied on get_original_terragrunt_dir() to locate sibling files. The fix introduces a dedicated WithDependencyConfigPath method that correctly resets the original config path when parsing a dependency as an independent unit.