FE: Update policies list to have a Source column

Why are we doing this work

• with inherited policies showing up on the policies list, a user will need an indication of where the policy came from (e.g. this project/group/namespace/instance)

Relevant links

Non-functional requirements

• Documentation:
• Testing:

Implementation plan

• frontend modify policies_list.vue to include a source column

- [ ] frontend modify scan_execution_policies graphql query to retrieve source information (updatedAt can be used for date/time information) Designs changed so that the the Last modified column stays where it is and continues to be default sorted