feat: Integrate includes into units reading

[yhakbar]

Description

Integrates the logic from --terragrunt-modules-that-include into --terragrunt-queue-include-units-reading.

Upon starting integration into Gruntwork Pipelines, it was discovered that there wasn't really a purpose to having two separate flags for this functionality. The --terragrunt-modules-that-include flag can remain supported for backwards compatibility and to ensure that users can still use it if they specifically want to include only the units that include particular configurations.

TODOs

Read the Gruntwork contribution guidelines.

• [x] Update the docs.
• [x] Run the relevant tests successfully, including pre-commit checks.
• [x] Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.
• [x] Include release notes. If this PR is backward incompatible, include a migration guide.

Release Notes (draft)

Updated --terragrunt-queue-include-units-reading to include the inclusion logic from --terragrunt-modules-that-include.