Draft: Add code suggestions Add-on helper methods to namespace

What does this MR do and why?

Add Code Suggestions Add-on helper methods to namespace:

• Add code_suggestions_add_on_compatible? method to determine if a given namespace is eligible for code suggestion add on purchases.
• Add code_suggestions_add_on_purchased? method to determine if a given top level group has an active Code Suggestions Add-on purchase.

Note: These methods are not used ATM. These are introduced as part of a cross team collaboration to be used by future policy definitions.

Screenshots or screen recordings

Does not apply.

How to set up and validate locally

These methods are not used yet. Green build should be enough.

Optional: The methods can be tested via console by calling these for existing namespaces.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #408499