chore(rename): move llama_stack.distribution to llama_stack.core (#2975)

We would like to rename the term `template` to `distribution`. To
prepare for that, this is a precursor.

cc @leseb

llama_stack/core/routers/safety.py

@@ -0,0 +1,58 @@
+# 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 Any
+
+from llama_stack.apis.inference import (
+    Message,
+)
+from llama_stack.apis.safety import RunShieldResponse, Safety
+from llama_stack.apis.shields import Shield
+from llama_stack.log import get_logger
+from llama_stack.providers.datatypes import RoutingTable
+
+logger = get_logger(name=__name__, category="core")
+
+
+class SafetyRouter(Safety):
+    def __init__(
+        self,
+        routing_table: RoutingTable,
+    ) -> None:
+        logger.debug("Initializing SafetyRouter")
+        self.routing_table = routing_table
+
+    async def initialize(self) -> None:
+        logger.debug("SafetyRouter.initialize")
+        pass
+
+    async def shutdown(self) -> None:
+        logger.debug("SafetyRouter.shutdown")
+        pass
+
+    async def register_shield(
+        self,
+        shield_id: str,
+        provider_shield_id: str | None = None,
+        provider_id: str | None = None,
+        params: dict[str, Any] | None = None,
+    ) -> Shield:
+        logger.debug(f"SafetyRouter.register_shield: {shield_id}")
+        return await self.routing_table.register_shield(shield_id, provider_shield_id, provider_id, params)
+
+    async def run_shield(
+        self,
+        shield_id: str,
+        messages: list[Message],
+        params: dict[str, Any] = None,
+    ) -> RunShieldResponse:
+        logger.debug(f"SafetyRouter.run_shield: {shield_id}")
+        provider = await self.routing_table.get_provider_impl(shield_id)
+        return await provider.run_shield(
+            shield_id=shield_id,
+            messages=messages,
+            params=params,
+        )