Add a RoutableProvider protocol, support for multiple routing keys (#163)

* Update configure.py to use multiple routing keys for safety
* Refactor distribution/datatypes into a providers/datatypes
* Cleanup

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

@@ -4,6 +4,8 @@
 # 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
 
@@ -14,7 +16,7 @@ class TogetherImplConfig(BaseModel):
         default="https://api.together.xyz/v1",
         description="The URL for the Together AI server",
     )
-    api_key: str = Field(
-        default="",
+    api_key: Optional[str] = Field(
+        default=None,
         description="The Together AI API Key",
     )