feat(tests): introduce a test "suite" concept to encompass dirs, options (#3339)

Our integration tests need to be 'grouped' because each group often
needs a specific set of models it works with. We separated vision tests
due to this, and we have a separate set of tests which test "Responses"
API.

This PR makes this system a bit more official so it is very easy to
target these groups and apply all testing infrastructure towards all the
groups (for example, record-replay) uniformly.

There are three suites declared:
- base
- vision
- responses

Note that our CI currently runs the "base" and "vision" suites.

You can use the `--suite` option when running pytest (or any of the
testing scripts or workflows.) For example:
```
OLLAMA_URL=http://localhost:11434 \
  pytest -s -v tests/integration/ --stack-config starter --suite vision
```

.github/actions/setup-ollama/action.yml

@@ -1,17 +1,17 @@
 name: Setup Ollama
 description: Start Ollama
 inputs:
-  run-vision-tests:
-    description: 'Run vision tests: "true" or "false"'
+  test-suite:
+    description: 'Test suite to use: base, responses, vision, etc.'
     required: false
-    default: 'false'
+    default: ''
 runs:
   using: "composite"
   steps:
     - name: Start Ollama
       shell: bash
       run: |
-        if [ "${{ inputs.run-vision-tests }}" == "true" ]; then
+        if [ "${{ inputs.test-suite }}" == "vision" ]; then
           image="ollama-with-vision-model"
         else
           image="ollama-with-models"