Split safety into (llama-guard, prompt-guard, code-scanner) (#400)

Splits the meta-reference safety implementation into three distinct providers:

- inline::llama-guard
- inline::prompt-guard
- inline::code-scanner

Note that this PR is a backward incompatible change to the llama stack server. I have added deprecation_error field to ProviderSpec -- the server reads it and immediately barfs. This is used to direct the user with a specific message on what action to perform. An automagical "config upgrade" is a bit too much work to implement right now :/

(Note that we will be gradually prefixing all inline providers with inline:: -- I am only doing this for this set of new providers because otherwise existing configuration files will break even more badly.)

llama_stack/providers/registry/safety.py

@@ -29,6 +29,43 @@ def available_providers() -> List[ProviderSpec]:
             api_dependencies=[
                 Api.inference,
             ],
+            deprecation_error="""
+Provider `meta-reference` for API `safety` does not work with the latest Llama Stack.
+
+- if you are using Llama Guard v3, please use the `inline::llama-guard` provider instead.
+- if you are using Prompt Guard, please use the `inline::prompt-guard` provider instead.
+- if you are using Code Scanner, please use the `inline::code-scanner` provider instead.
+
+            """,
+        ),
+        InlineProviderSpec(
+            api=Api.safety,
+            provider_type="inline::llama-guard",
+            pip_packages=[],
+            module="llama_stack.providers.inline.safety.llama_guard",
+            config_class="llama_stack.providers.inline.safety.llama_guard.LlamaGuardConfig",
+            api_dependencies=[
+                Api.inference,
+            ],
+        ),
+        InlineProviderSpec(
+            api=Api.safety,
+            provider_type="inline::prompt-guard",
+            pip_packages=[
+                "transformers",
+                "torch --index-url https://download.pytorch.org/whl/cpu",
+            ],
+            module="llama_stack.providers.inline.safety.prompt_guard",
+            config_class="llama_stack.providers.inline.safety.prompt_guard.PromptGuardConfig",
+        ),
+        InlineProviderSpec(
+            api=Api.safety,
+            provider_type="inline::code-scanner",
+            pip_packages=[
+                "codeshield",
+            ],
+            module="llama_stack.providers.inline.safety.code_scanner",
+            config_class="llama_stack.providers.inline.safety.code_scanner.CodeScannerConfig",
         ),
         remote_provider_spec(
             api=Api.safety,
@@ -48,14 +85,4 @@ def available_providers() -> List[ProviderSpec]:
                 config_class="llama_stack.providers.remote.safety.bedrock.BedrockSafetyConfig",
             ),
         ),
-        InlineProviderSpec(
-            api=Api.safety,
-            provider_type="meta-reference/codeshield",
-            pip_packages=[
-                "codeshield",
-            ],
-            module="llama_stack.providers.inline.safety.meta_reference",
-            config_class="llama_stack.providers.inline.safety.meta_reference.CodeShieldConfig",
-            api_dependencies=[],
-        ),
     ]