Split construct policy methods by type

What does this MR do and why?

Split construct policy methods by type

Construct security policies methods are divided by type into separate modules

This change refactors the security policy construction code by breaking down a large monolithic module into smaller, more focused modules. The original ConstructSecurityPolicies module contained all the logic for different types of policies (scan execution, approval, vulnerability management, pipeline execution, etc.). Now, each policy type has its own dedicated module with specific construction methods. Common functionality has been extracted into a shared ConstructSecurityPoliciesSharedAttributes module that defines constants and helper methods used across all policy types. This reorganization improves code maintainability by following the single responsibility principle, making each module focused on constructing just one type of policy while sharing common code. The functionality remains the same, but the code structure is now more modular and easier to maintain.

References

Screenshots or screen recordings

***NO VISUAL CHANGES***

How to set up and validate locally

1. Go to graphql-explorer and test a query

   {
     group(fullPath: "full-path") {
       approvalPolicies {
         nodes {
           description
           name
         }
       }
       pipelineExecutionPolicies {
         nodes {
           name
         }
       }
       pipelineExecutionSchedulePolicies {
         nodes {
           name
         }
       }
       scanExecutionPolicies {
         nodes {
           name
         }
       }
       approvalPolicies {
         nodes {
           name
         }
       }
       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 #537450 (closed)