Support targeting the root folder of the target GitOps directory using the prer tool

[kzadorozhny]

Description

The create_gitops_prs tool now accommodates the scenario where the --gitops_path parameter is omitted, enabling .gitops rules to control the layout of gitops manifests from the root folder of the destination repository.

Related Issue

Motivation and Context

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.