Expose policy_scope in security policy graphql API

What does this MR do and why?

This MR reinstates the revert MR !146386 (merged) due to gitlab-com/gl-infra/production#17690 (closed)

As a part of Support existing policies as we introduce polic... (#432513 - closed), we want to expose the policy_scope in the graphql query with the compliance frameworks and the projects.

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How to set up and validate locally

1. Create a root level group and create a compliance framework
2. Create Approval policy with policy scope:

type: approval_policy
name: SRP
description: ''
enabled: true
rules:
  - type: scan_finding
    scanners: []
    vulnerabilities_allowed: 0
    severity_levels: []
    vulnerability_states: []
    branch_type: protected
actions:
  - type: require_approval
    approvals_required: 1
    group_approvers_ids:
      - <ID>
policy_scope:
  compliance_frameworks:
    - id: <ID>

3. Enable security_policies_policy_scope feature flag: Feature.enable(:security_policies_policy_scope, group) and enable the Security policy scope experimental feature by going to Settings -> General -> Permissions & Group features -> Select Security Policy Scopes checkbox
4. Go to graphql-explorer and query for approvalPolicies

query{
  group(fullPath:"compliance-policies") {
    approvalPolicies {
      nodes {
        policyScope {
          complianceFrameworks {
            nodes {
              id
              name
            }
          }
          includingProjects {
            nodes {
              id
            }
          }
          excludingProjects {
            nodes {
              id
            }
          }
        }
      }
    }    
  }
}

Addresses #432513 (closed)