Implement probes for checking self-hosted, offline instance AIGW installation

Problem to solve

Installing and configuring AIGW can be challenging, and we added scripts to make debugging easier. This differs to how connection is tested against CloudConnect, which shows those tests in the UI.

The purpose of this issue is to make this testing easier and to better align with the CloudConnect approach.

Definition of Done

1. Target for probes are the three checks found in this code
   • Environment variables are correct verify_environmental_variables!
   • License is correct verify_license_access!
   • AI Gateway is reachable verify_aigateway_access!
2. Create three probes in this code for those checks
3. Update the Vue component's probe-to-section mapping and hide any empty sections. Display results of probes (#491564 - closed)
4. The original checks can now be deleted as we have turned them into probes?