FE: Update the `Status` column in the Policy table to be a checkbox

Why are we doing this work

• Users want to easily see if a policy is enabled or not visually

Relevant links

Design: https://gitlab.com/groups/gitlab-org/-/uploads/7e0dd6a4bfff1a85672bcf58ecb86d0c/policies-states.png

Non-functional requirements

• [-] Documentation
  • [-] Update screenshots if needed.
• Testing
  • Renders correct icon and tooltip for enabled policies.
  • Does not render anything for disabled policies.

Implementation plan

• frontend update the status column in https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/assets/javascripts/threat_monitoring/components/network_policy_list.vue to match designs
  • It should be the table's left-most column.
  • It should not have a label.
  • Enabled policies should have a checkmark icon and a tooltip stating Enabled.
  • The cell should be left empty for disabled policies.