chore: mypy violations cleanup for inline::{telemetry,tool_runtime,vector_io} (#1711)

# What does this PR do?

Clean up mypy violations for inline::{telemetry,tool_runtime,vector_io}.
This also makes API accept a tool call result without any content (like
RAG tool already may produce).

Signed-off-by: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>

llama_stack/apis/tools/tools.py

@@ -69,7 +69,7 @@ class ToolGroup(Resource):
 
 @json_schema_type
 class ToolInvocationResult(BaseModel):
-    content: InterleavedContent
+    content: Optional[InterleavedContent] = None
     error_message: Optional[str] = None
     error_code: Optional[int] = None
     metadata: Optional[Dict[str, Any]] = None
@@ -140,9 +140,9 @@ class SpecialToolGroup(Enum):
 @runtime_checkable
 @trace_protocol
 class ToolRuntime(Protocol):
-    tool_store: ToolStore
+    tool_store: ToolStore | None = None
 
-    rag_tool: RAGToolRuntime
+    rag_tool: RAGToolRuntime | None = None
 
     # TODO: This needs to be renamed once OPEN API generator name conflict issue is fixed.
     @webmethod(route="/tool-runtime/list-tools", method="GET")

llama_stack/apis/vector_io/vector_io.py

@@ -36,7 +36,7 @@ class VectorDBStore(Protocol):
 @runtime_checkable
 @trace_protocol
 class VectorIO(Protocol):
-    vector_db_store: VectorDBStore
+    vector_db_store: VectorDBStore | None = None
 
     # this will just block now until chunks are inserted, but it should
     # probably return a Job instance which can be polled for completion