feat: ability to execute external providers (#1672)

# What does this PR do?

Providers that live outside of the llama-stack codebase are now
supported.
A new property `external_providers_dir` has been added to the main
config and can be configured as follow:

```
external_providers_dir: /etc/llama-stack/providers.d/
```

Where the expected structure is:

```
providers.d/
  inference/
    custom_ollama.yaml
    vllm.yaml
  vector_io/
    qdrant.yaml
```

Where `custom_ollama.yaml` is:

```
adapter:
  adapter_type: custom_ollama
  pip_packages: ["ollama", "aiohttp"]
  config_class: llama_stack_ollama_provider.config.OllamaImplConfig
  module: llama_stack_ollama_provider
api_dependencies: []
optional_api_dependencies: []
```

Obviously the package must be installed on the system, here is the
`llama_stack_ollama_provider` example:

```
$ uv pip show llama-stack-ollama-provider
Using Python 3.10.16 environment at: /Users/leseb/Documents/AI/llama-stack/.venv
Name: llama-stack-ollama-provider
Version: 0.1.0
Location: /Users/leseb/Documents/AI/llama-stack/.venv/lib/python3.10/site-packages
Editable project location: /private/var/folders/mq/rnm5w_7s2d3fxmtkx02knvhm0000gn/T/tmp.ZBHU5Ezxg4/ollama/llama-stack-ollama-provider
Requires:
Required-by:
```

Closes: https://github.com/meta-llama/llama-stack/issues/658

Signed-off-by: Sébastien Han <seb@redhat.com>

tests/external-provider/llama-stack-provider-ollama/README.md

@@ -0,0 +1,3 @@
+# Ollama external provider for Llama Stack
+
+Template code to create a new external provider for Llama Stack.

tests/external-provider/llama-stack-provider-ollama/custom_ollama.yaml

@@ -0,0 +1,7 @@
+adapter:
+  adapter_type: custom_ollama
+  pip_packages: ["ollama", "aiohttp"]
+  config_class: llama_stack_provider_ollama.config.OllamaImplConfig
+  module: llama_stack_provider_ollama
+api_dependencies: []
+optional_api_dependencies: []

tests/external-provider/llama-stack-provider-ollama/pyproject.toml

@@ -0,0 +1,44 @@
+[project]
+dependencies = [
+    "llama-stack",
+    "pydantic",
+    "ollama",
+    "aiohttp",
+    "aiosqlite",
+    "autoevals",
+    "blobfile",
+    "chardet",
+    "chromadb-client",
+    "datasets",
+    "faiss-cpu",
+    "fastapi",
+    "fire",
+    "httpx",
+    "matplotlib",
+    "mcp",
+    "nltk",
+    "numpy",
+    "openai",
+    "opentelemetry-exporter-otlp-proto-http",
+    "opentelemetry-sdk",
+    "pandas",
+    "pillow",
+    "psycopg2-binary",
+    "pymongo",
+    "pypdf",
+    "redis",
+    "requests",
+    "scikit-learn",
+    "scipy",
+    "sentencepiece",
+    "tqdm",
+    "transformers",
+    "tree_sitter",
+    "uvicorn",
+]
+
+name = "llama-stack-provider-ollama"
+version = "0.1.0"
+description = "External provider for Ollama using the Llama Stack API"
+readme = "README.md"
+requires-python = ">=3.10"

tests/external-provider/llama-stack-provider-ollama/run.yaml

@@ -0,0 +1,135 @@
+version: '2'
+image_name: ollama
+apis:
+- agents
+- datasetio
+- eval
+- inference
+- safety
+- scoring
+- telemetry
+- tool_runtime
+- vector_io
+providers:
+  inference:
+  - provider_id: custom_ollama
+    provider_type: remote::custom_ollama
+    config:
+      url: ${env.OLLAMA_URL:http://localhost:11434}
+  vector_io:
+  - provider_id: faiss
+    provider_type: inline::faiss
+    config:
+      kvstore:
+        type: sqlite
+        namespace: null
+        db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/ollama}/faiss_store.db
+  safety:
+  - provider_id: llama-guard
+    provider_type: inline::llama-guard
+    config:
+      excluded_categories: []
+  agents:
+  - provider_id: meta-reference
+    provider_type: inline::meta-reference
+    config:
+      persistence_store:
+        type: sqlite
+        namespace: null
+        db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/ollama}/agents_store.db
+  telemetry:
+  - provider_id: meta-reference
+    provider_type: inline::meta-reference
+    config:
+      service_name: ${env.OTEL_SERVICE_NAME:llama-stack}
+      sinks: ${env.TELEMETRY_SINKS:console,sqlite}
+      sqlite_db_path: ${env.SQLITE_DB_PATH:~/.llama/distributions/ollama/trace_store.db}
+  eval:
+  - provider_id: meta-reference
+    provider_type: inline::meta-reference
+    config:
+      kvstore:
+        type: sqlite
+        namespace: null
+        db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/ollama}/meta_reference_eval.db
+  datasetio:
+  - provider_id: huggingface
+    provider_type: remote::huggingface
+    config:
+      kvstore:
+        type: sqlite
+        namespace: null
+        db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/ollama}/huggingface_datasetio.db
+  - provider_id: localfs
+    provider_type: inline::localfs
+    config:
+      kvstore:
+        type: sqlite
+        namespace: null
+        db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/ollama}/localfs_datasetio.db
+  scoring:
+  - provider_id: basic
+    provider_type: inline::basic
+    config: {}
+  - provider_id: llm-as-judge
+    provider_type: inline::llm-as-judge
+    config: {}
+  - provider_id: braintrust
+    provider_type: inline::braintrust
+    config:
+      openai_api_key: ${env.OPENAI_API_KEY:}
+  tool_runtime:
+  - provider_id: brave-search
+    provider_type: remote::brave-search
+    config:
+      api_key: ${env.BRAVE_SEARCH_API_KEY:}
+      max_results: 3
+  - provider_id: tavily-search
+    provider_type: remote::tavily-search
+    config:
+      api_key: ${env.TAVILY_SEARCH_API_KEY:}
+      max_results: 3
+  - provider_id: code-interpreter
+    provider_type: inline::code-interpreter
+    config: {}
+  - provider_id: rag-runtime
+    provider_type: inline::rag-runtime
+    config: {}
+  - provider_id: model-context-protocol
+    provider_type: remote::model-context-protocol
+    config: {}
+  - provider_id: wolfram-alpha
+    provider_type: remote::wolfram-alpha
+    config:
+      api_key: ${env.WOLFRAM_ALPHA_API_KEY:}
+metadata_store:
+  type: sqlite
+  db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/ollama}/registry.db
+models:
+- metadata: {}
+  model_id: ${env.INFERENCE_MODEL}
+  provider_id: custom_ollama
+  model_type: llm
+- metadata:
+    embedding_dimension: 384
+  model_id: all-MiniLM-L6-v2
+  provider_id: custom_ollama
+  provider_model_id: all-minilm:latest
+  model_type: embedding
+shields: []
+vector_dbs: []
+datasets: []
+scoring_fns: []
+benchmarks: []
+tool_groups:
+- toolgroup_id: builtin::websearch
+  provider_id: tavily-search
+- toolgroup_id: builtin::rag
+  provider_id: rag-runtime
+- toolgroup_id: builtin::code_interpreter
+  provider_id: code-interpreter
+- toolgroup_id: builtin::wolfram_alpha
+  provider_id: wolfram-alpha
+server:
+  port: 8321
+external_providers_dir: /tmp/providers.d