Query list of all policy types

What does this MR do and why?

Add flat policy list of all types

User can query a list of all policies of mixed type

Changelog: changed EE: true

References

Screenshots or screen recordings

Description	UI
New query for a flat list

How to set up and validate locally

1. Go to http://base_url/-/graphql-explorer

2. Query:

   {
     group(fullPath: "path") {
       securityPolicies(includeUnscoped: false) {
         nodes {
           name
           type
           enabled
           updatedAt
           editPath
           policyAttributes {
             ...on PipelineExecutionScheduledPolicyAttributesType{
               policyBlobFilePath
               warnings
             }
             ...on ScanExecutionPolicyAttributesType {
               deprecatedProperties
               source {
                 __typename
               }
             }
             ... on ApprovalPolicyAttributesType {
               __typename
               actionApprovers {
                 users {
                   name
                 }
               }
             }
             ...on VulnerabilityManagementPolicyAttributesType {
               source {
                 ...on GroupSecurityPolicySource {
                   namespace {
                     name
                   }
                 }
               }
             }
             ...on PipelineExecutionPolicyAttributesType {
               policyBlobFilePath
             }
           }
         }
         pageInfo {
           hasNextPage
           hasPreviousPage
           endCursor
           startCursor
         }
       }
       
     }
   }
         
   

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Related to #545696 (closed)