feat: user defined custom tools as part of workflow execution (#94)

* feat: add custom tools functionality

* Show tools in nodes

* integrate tool calling with pipeline engine

api/services/workflow/dto.py

@@ -57,6 +57,7 @@ class NodeDataDTO(BaseModel):
     detect_voicemail: bool = False
     delayed_start: bool = False
     delayed_start_duration: Optional[float] = None
+    tool_uuids: Optional[List[str]] = None
     trigger_path: Optional[str] = None
     # Webhook node specific fields
     enabled: bool = True