title: spark structured streaming parquet overwrite
body: <p>i would like to be able to overwrite my output path with parquet format, 
  but it's not among available actions (append, complete, update), 
  Is there another solution here ? </p>
  
  <pre><code>val streamDF = sparkSession.readStream.schema(schema).option("header","true").parquet(rawData)
  
  val query = streamDF.writeStream.outputMode("overwrite").format("parquet").option("checkpointLocation",checkpoint).start(target)
  query.awaitTermination()
  </code></pre>