feat: allow for provider immutability

being able to update providers means that admins should have the ability to turn this feature off. introduce `immutable` as a field in the Provider class. Defauling to false means all providers can be updated by default, but an admin at runtime can choose to set this to True to disable provider updating

Signed-off-by: Charlie Doern <cdoern@redhat.com>

llama_stack/templates/postgres-demo/run.yaml

@@ -16,19 +16,23 @@ providers:
       max_tokens: ${env.VLLM_MAX_TOKENS:=4096}
       api_token: ${env.VLLM_API_TOKEN:=fake}
       tls_verify: ${env.VLLM_TLS_VERIFY:=true}
+    immutable: false
   - provider_id: sentence-transformers
     provider_type: inline::sentence-transformers
     config: {}
+    immutable: false
   vector_io:
   - provider_id: ${env.ENABLE_CHROMADB:+chromadb}
     provider_type: remote::chromadb
     config:
       url: ${env.CHROMADB_URL:=}
+    immutable: false
   safety:
   - provider_id: llama-guard
     provider_type: inline::llama-guard
     config:
       excluded_categories: []
+    immutable: false
   agents:
   - provider_id: meta-reference
     provider_type: inline::meta-reference
@@ -47,6 +51,7 @@ providers:
         db: ${env.POSTGRES_DB:=llamastack}
         user: ${env.POSTGRES_USER:=llamastack}
         password: ${env.POSTGRES_PASSWORD:=llamastack}
+    immutable: false
   telemetry:
   - provider_id: meta-reference
     provider_type: inline::meta-reference
@@ -54,23 +59,28 @@ providers:
       service_name: ${env.OTEL_SERVICE_NAME:=}
       sinks: ${env.TELEMETRY_SINKS:=console,otel_trace}
       otel_trace_endpoint: ${env.OTEL_TRACE_ENDPOINT:=http://localhost:4318/v1/traces}
+    immutable: false
   tool_runtime:
   - provider_id: brave-search
     provider_type: remote::brave-search
     config:
       api_key: ${env.BRAVE_SEARCH_API_KEY:=}
       max_results: 3
+    immutable: false
   - provider_id: tavily-search
     provider_type: remote::tavily-search
     config:
       api_key: ${env.TAVILY_SEARCH_API_KEY:=}
       max_results: 3
+    immutable: false
   - provider_id: rag-runtime
     provider_type: inline::rag-runtime
     config: {}
+    immutable: false
   - provider_id: model-context-protocol
     provider_type: remote::model-context-protocol
     config: {}
+    immutable: false
 metadata_store:
   type: postgres
   host: ${env.POSTGRES_HOST:=localhost}