Spark DataSets using OSMEntity case classes

[angelcervera]

At the moment, the Spark connector is using DataFrames. It would be useful to allow direct interaction between OSMEntity types and the Spark Connector using DataSets.

Something like these cases should work.

      import spark.implicits._
      val dataset = Seq(
        NodeEntity(1, 11, 10, Map({ "nodeId" -> "1"})),
        NodeEntity(2, 12, 20, Map({ "nodeId" -> "2"})),
        NodeEntity(3, 13, 30, Map.empty),
        NodeEntity(4, 14, 40, Map.empty),
        NodeEntity(5, 15, 50, Map.empty),
        NodeEntity(6, 16, 60, Map.empty),
        WayEntity(7, Seq(1,2,3,4), Map({ "wayId" -> "7"})),
        WayEntity(8, Seq(4,5,6), Map({ "wayId" -> "8"})),
      ).toDS()

      dataset.show()

Or

      import spark.implicits._
      val monaco = spark.sqlContext.read
        .format("osm.pbf")
        .load("src/test/resources/monaco.osm.pbf")
        .persist()

      monaco.as[OSMEntity]