Add Runpod Provider + Distribution (#362)

Add Runpod as a inference provider for openAI compatible managed
endpoints.

Testing 
- Configured llama stack from scratch, set `remote::runpod` as a
inference provider.
- Added Runpod Endpoint URL and API key. 
- Started llama-stack server - llama stack run my-local-stack --port
3000
```
curl http://localhost:5000/inference/chat_completion \
-H "Content-Type: application/json" \
-d '{
	"model": "Llama3.1-8B-Instruct",
	"messages": [
		{"role": "system", "content": "You are a helpful assistant."},
		{"role": "user", "content": "Write me a 2 sentence poem about the moon"}
	],
	"sampling_params": {"temperature": 0.7, "seed": 42, "max_tokens": 512}
}' ```

---------

Signed-off-by: pandyamarut <pandyamarut@gmail.com>

llama_stack/providers/adapters/inference/runpod/config.py

@@ -0,0 +1,22 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from typing import Optional
+
+from llama_models.schema_utils import json_schema_type
+from pydantic import BaseModel, Field
+
+
+@json_schema_type
+class RunpodImplConfig(BaseModel):
+    url: Optional[str] = Field(
+        default=None,
+        description="The URL for the Runpod model serving endpoint",
+    )
+    api_token: Optional[str] = Field(
+        default=None,
+        description="The API token",
+    )