Creates an optional StreamWriter to save the data to this data source. Data
sources can return None if there is no writing needed to be done.
queryId - A unique string for the writing query. It's possible that there are many
writing queries running at the same time, and the returned
DataSourceWriter can use this id to distinguish itself from others.
schema - the schema of the data to be written.
mode - the output mode which determines what successive epoch output means to this
sink, please refer to OutputMode for more details.
options - the options for the returned data source writer, which is an immutable
case-insensitive string-to-string map.