FE: Fetch scan execution policies in policy list

Why are we doing this work

We want to display scan execution policies along with network policies in Threat Monitoring. Now that the backend supports it, the frontend can fetch scan execution policies and display them in the list.

Relevant links

• Epic: &5362 (closed)
• Issue for creating the scan execution policies GraphQL endpoint: #329423 (closed)

Non-functional requirements

• Testing:
  • GraphQL query is triggered.

Implementation plan

• Create the scan_execution_policies.query.graphql query.
• Trigger the query from NetworkPolicyList.
• Display fetched items in the list.