Create group `policies#new` page

Why are we doing this work

• a user wants to be able to create group-wide policies

Relevant links

Non-functional requirements

• Documentation:
• Feature flag: :group_security_policies
• Testing:

Implementation plan

• backend Create groups/<GROUP_NAME>/-/security/policies/new path to create a new policy
  • new controller:ee/app/controllers/groups/security/policies_controller.rb, new route:#new, new view: ee/app/views/groups/security/policies/new.html.haml
• backend ensure all the correct information is being passed to the frontend (per !84393 (comment 901447787))
  • modify policies_helper.rb to work for group policies and project policies
• frontend copy ee/app/assets/javascripts/pages/projects/security/policies/new/index.js to create the ee/app/assets/javascripts/pages/group/security/policies/new/index.js
• frontend modify update_scan_execution_policies query (or create a new group-level one) to create/update/destroy group-level policies
• frontend modify policies_editor.vue to work for group-level policies
• frontend show an informational alert that the policy will affect many projects and link back to the Group Overview page