Refactor SparkIngestor to a configurable component

[kevinwallimann]

Currently, the SparkIngestor doesn't accept any configuration. This will be needed for long-running jobs to choose either StreamingQuery.awaitTermination or StreamingQuery.processAllAvailable.

Additionally, it's currently not possible to pass configuration options to the sparksession via the config file or command line

Tasks

• Make SparkIngestor a class that accepts a SparkSession and Configuration which is instantiated by a companion object, much like the other components e.g. KafkaStreamReader etc.
• Pass all options with prefix ingestor.spark.options. on to the SparkSession

[kevinwallimann]

Close PR because extra options for spark would be overwritten by options passed to spark-submit