Expose CSP flag for the namespace type

What does this MR do and why?

Expose CSP for the namespace type

• Allow querying designated_as_csp in GQL for the namespace type
• Expose designated_as_csp for frontend via SecurityOrchestrationHelper

Policies GQL will be extended in Expose `csp` in GQL for all policy types (!192672 - merged).

References

Screenshots or screen recordings

Without CSP	With CSP

How to set up and validate locally

1. Enable the feature flag:

   Feature.enable(:security_policies_csp)

2. Create a top-level group and assign it as a CSP using rails console:

   Security::PolicySetting.instance.update! csp_namespace: Group.find(<group_id>)

3. Using /-/graphql-explorer, run the following query:

   {
     namespace(fullPath: "csp-group") {
       id
       designatedAsCsp
     }
   }

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Related to #541510 (closed)