Broader than the simple FunctionTransform, this trait allows transforms to write to
multiple outputs. Those outputs must be known in advanced and returned via
TransformConfig::outputs. Attempting to send to any output not registered in advance is
considered a bug and will cause a panic.
event: The event that will be updated
output_id: The output_id that the current even is being sent to (will be used as the new parent_id)
log_schema_definitions: A mapping of parent OutputId to definitions, that will be used to lookup the new runtime definition of the event