Add multiple approvers action support for graphql api

What does this MR do and why?

Add multiple approvers action support

Security orchestration helper now support multiple approvers actions

1. Old API is preserved for a backward compatibility
2. New API adds new field action_approvers, it returns array of action Approvers

References

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Description	UI
New GraphQl field

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Checkout branch
2. Go to a /-/graphql-explorer
3. Check query:

{
  group(fullPath: "path-to-a-group") {
    approvalPolicies {
      nodes {
        name
      	actionApprovers {
          groups {
            fullPath
          }
          roles
          users {
            name
          }
        }    
      }
    }
  }
}

Related to #493744 (closed)