feat(providers): Groq now uses LiteLLM openai-compat (#1303)

Groq has never supported raw completions anyhow. So this makes it easier
to switch it to LiteLLM. All our test suite passes.

I also updated all the openai-compat providers so they work with api
keys passed from headers. `provider_data`

## Test Plan

```bash
LLAMA_STACK_CONFIG=groq \
   pytest -s -v tests/client-sdk/inference/test_text_inference.py \
   --inference-model=groq/llama-3.3-70b-versatile --vision-inference-model=""
```

Also tested (openai, anthropic, gemini) providers. No regressions.

llama_stack/templates/dev/build.yaml

@@ -7,6 +7,7 @@ distribution_spec:
     - remote::fireworks
     - remote::anthropic
     - remote::gemini
+    - remote::groq
     - inline::sentence-transformers
     vector_io:
     - inline::sqlite-vec