Add provider deprecation support; change directory structure (#397)

* Add provider deprecation support; change directory structure

* fix a couple dangling imports

* move the meta_reference safety dir also

llama_stack/providers/inline/safety/meta_reference/base.py

@@ -0,0 +1,57 @@
+# 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 abc import ABC, abstractmethod
+from typing import List
+
+from llama_models.llama3.api.datatypes import interleaved_text_media_as_str, Message
+from pydantic import BaseModel
+from llama_stack.apis.safety import *  # noqa: F403
+
+CANNED_RESPONSE_TEXT = "I can't answer that. Can I help with something else?"
+
+
+# TODO: clean this up; just remove this type completely
+class ShieldResponse(BaseModel):
+    is_violation: bool
+    violation_type: Optional[str] = None
+    violation_return_message: Optional[str] = None
+
+
+# TODO: this is a caller / agent concern
+class OnViolationAction(Enum):
+    IGNORE = 0
+    WARN = 1
+    RAISE = 2
+
+
+class ShieldBase(ABC):
+    def __init__(
+        self,
+        on_violation_action: OnViolationAction = OnViolationAction.RAISE,
+    ):
+        self.on_violation_action = on_violation_action
+
+    @abstractmethod
+    async def run(self, messages: List[Message]) -> ShieldResponse:
+        raise NotImplementedError()
+
+
+def message_content_as_str(message: Message) -> str:
+    return interleaved_text_media_as_str(message.content)
+
+
+class TextShield(ShieldBase):
+    def convert_messages_to_text(self, messages: List[Message]) -> str:
+        return "\n".join([message_content_as_str(m) for m in messages])
+
+    async def run(self, messages: List[Message]) -> ShieldResponse:
+        text = self.convert_messages_to_text(messages)
+        return await self.run_impl(text)
+
+    @abstractmethod
+    async def run_impl(self, text: str) -> ShieldResponse:
+        raise NotImplementedError()