feat: add oci genai service as chat inference provider (#3876)

# What does this PR do?
Adds OCI GenAI PaaS models for openai chat completion endpoints.

## Test Plan
In an OCI tenancy with access to GenAI PaaS, perform the following
steps:

1. Ensure you have IAM policies in place to use service (check docs
included in this PR)
2. For local development, [setup OCI
cli](https://docs.oracle.com/en-us/iaas/Content/API/SDKDocs/cliinstall.htm)
and configure the CLI with your region, tenancy, and auth
[here](https://docs.oracle.com/en-us/iaas/Content/API/SDKDocs/cliconfigure.htm)
3. Once configured, go through llama-stack setup and run llama-stack
(uses config based auth) like:
```bash
OCI_AUTH_TYPE=config_file \
OCI_CLI_PROFILE=CHICAGO \
OCI_REGION=us-chicago-1 \
OCI_COMPARTMENT_OCID=ocid1.compartment.oc1..aaaaaaaa5...5a \
llama stack run oci
```
4. Hit the `models` endpoint to list models after server is running:
```bash
curl http://localhost:8321/v1/models | jq
...
{
      "identifier": "meta.llama-4-scout-17b-16e-instruct",
      "provider_resource_id": "ocid1.generativeaimodel.oc1.us-chicago-1.am...q",
      "provider_id": "oci",
      "type": "model",
      "metadata": {
        "display_name": "meta.llama-4-scout-17b-16e-instruct",
        "capabilities": [
          "CHAT"
        ],
        "oci_model_id": "ocid1.generativeaimodel.oc1.us-chicago-1.a...q"
      },
      "model_type": "llm"
},
   ...
```
5. Use the "display_name" field to use the model in a
`/chat/completions` request:
```bash
# Streaming result
curl -X POST http://localhost:8321/v1/chat/completions   -H "Content-Type: application/json"   -d '{
        "model": "meta.llama-4-scout-17b-16e-instruct",
       "stream": true,
       "temperature": 0.9,
      "messages": [
         {
           "role": "system",
           "content": "You are a funny comedian. You can be crass."
         },
          {
           "role": "user",
          "content": "Tell me a funny joke about programming."
         }
       ]
}'

# Non-streaming result
curl -X POST http://localhost:8321/v1/chat/completions   -H "Content-Type: application/json"   -d '{
        "model": "meta.llama-4-scout-17b-16e-instruct",
       "stream": false,
       "temperature": 0.9,
      "messages": [
         {
           "role": "system",
           "content": "You are a funny comedian. You can be crass."
         },
          {
           "role": "user",
          "content": "Tell me a funny joke about programming."
         }
       ]
}'
```
6. Try out other models from the `/models` endpoint.

src/llama_stack/distributions/oci/run.yaml

@@ -0,0 +1,136 @@
+version: 2
+image_name: oci
+apis:
+- agents
+- datasetio
+- eval
+- files
+- inference
+- safety
+- scoring
+- tool_runtime
+- vector_io
+providers:
+  inference:
+  - provider_id: oci
+    provider_type: remote::oci
+    config:
+      oci_auth_type: ${env.OCI_AUTH_TYPE:=instance_principal}
+      oci_config_file_path: ${env.OCI_CONFIG_FILE_PATH:=~/.oci/config}
+      oci_config_profile: ${env.OCI_CLI_PROFILE:=DEFAULT}
+      oci_region: ${env.OCI_REGION:=us-ashburn-1}
+      oci_compartment_id: ${env.OCI_COMPARTMENT_OCID:=}
+  vector_io:
+  - provider_id: faiss
+    provider_type: inline::faiss
+    config:
+      persistence:
+        namespace: vector_io::faiss
+        backend: kv_default
+  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:
+        agent_state:
+          namespace: agents
+          backend: kv_default
+        responses:
+          table_name: responses
+          backend: sql_default
+          max_write_queue_size: 10000
+          num_writers: 4
+  eval:
+  - provider_id: meta-reference
+    provider_type: inline::meta-reference
+    config:
+      kvstore:
+        namespace: eval
+        backend: kv_default
+  datasetio:
+  - provider_id: huggingface
+    provider_type: remote::huggingface
+    config:
+      kvstore:
+        namespace: datasetio::huggingface
+        backend: kv_default
+  - provider_id: localfs
+    provider_type: inline::localfs
+    config:
+      kvstore:
+        namespace: datasetio::localfs
+        backend: kv_default
+  scoring:
+  - provider_id: basic
+    provider_type: inline::basic
+  - provider_id: llm-as-judge
+    provider_type: inline::llm-as-judge
+  - 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: rag-runtime
+    provider_type: inline::rag-runtime
+  - provider_id: model-context-protocol
+    provider_type: remote::model-context-protocol
+  files:
+  - provider_id: meta-reference-files
+    provider_type: inline::localfs
+    config:
+      storage_dir: ${env.FILES_STORAGE_DIR:=~/.llama/distributions/oci/files}
+      metadata_store:
+        table_name: files_metadata
+        backend: sql_default
+storage:
+  backends:
+    kv_default:
+      type: kv_sqlite
+      db_path: ${env.SQLITE_STORE_DIR:=~/.llama/distributions/oci}/kvstore.db
+    sql_default:
+      type: sql_sqlite
+      db_path: ${env.SQLITE_STORE_DIR:=~/.llama/distributions/oci}/sql_store.db
+  stores:
+    metadata:
+      namespace: registry
+      backend: kv_default
+    inference:
+      table_name: inference_store
+      backend: sql_default
+      max_write_queue_size: 10000
+      num_writers: 4
+    conversations:
+      table_name: openai_conversations
+      backend: sql_default
+    prompts:
+      namespace: prompts
+      backend: kv_default
+registered_resources:
+  models: []
+  shields: []
+  vector_dbs: []
+  datasets: []
+  scoring_fns: []
+  benchmarks: []
+  tool_groups:
+  - toolgroup_id: builtin::websearch
+    provider_id: tavily-search
+server:
+  port: 8321
+telemetry:
+  enabled: true