refactor: move tests/client-sdk to tests/api (#1376)

This PR moves the client-sdk tests to the api directory to better
reflect their purpose and improve code organization.

tests/api/README.md

@@ -0,0 +1,31 @@
+# Llama Stack Integration Tests
+You can run llama stack integration tests on either a Llama Stack Library or a Llama Stack endpoint.
+
+To test on a Llama Stack library with certain configuration, run
+```bash
+LLAMA_STACK_CONFIG=./llama_stack/templates/cerebras/run.yaml pytest -s -v tests/api/inference/
+```
+or just the template name
+```bash
+LLAMA_STACK_CONFIG=together pytest -s -v tests/api/inference/
+```
+
+To test on a Llama Stack endpoint, run
+```bash
+LLAMA_STACK_BASE_URL=http://localhost:8089 pytest -s -v tests/api/inference
+```
+
+## Report Generation
+
+To generate a report, run with `--report` option
+```bash
+LLAMA_STACK_CONFIG=together pytest -s -v report.md tests/api/ --report
+```
+
+## Common options
+Depending on the API, there are custom options enabled
+- For tests in `inference/` and `agents/, we support `--inference-model` (to be used in text inference tests) and `--vision-inference-model` (only used in image inference tests) overrides
+- For tests in `vector_io/`, we support `--embedding-model` override
+- For tests in `safety/`, we support `--safety-shield` override
+- The param can be `--report` or `--report <path>`
+If path is not provided, we do a best effort to infer based on the config / template name. For url endpoints, path is required.