feat(verification): various improvements (#1921)

# What does this PR do?
- provider and their models now live in config.yaml
- better distinguish different cases within a test
- add model key to surface provider's model_id
- include example command to rerun single test case

## Test Plan
<img width="1173" alt="image"
src="https://github.com/user-attachments/assets/b414baf0-c768-451f-8c3b-c2905cf36fac"
/>

tests/verifications/conf/openai.yaml

@@ -0,0 +1,9 @@
+base_url: https://api.openai.com/v1
+api_key_var: OPENAI_API_KEY
+models:
+- gpt-4o
+- gpt-4o-mini
+model_display_names:
+  gpt-4o: gpt-4o
+  gpt-4o-mini: gpt-4o-mini
+test_exclusions: {}