Add bin/saas-feature helper script and document

What does this MR do and why?

Add bin/saas-feature helper script and document

• helper script to help ensure ease of standards
• see #427723 (closed)

note: All code/docs based on bin/feature-flag and modified as needed.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

Use the script locally.

Related to #427723 (closed)