QbeastOptions should follow the Builder Pattern

[osopardo1]

QbeastOptions is constructed by a Map of Strings containing (or not) different information for writing in a Qbeast table.

The structure of the builder is a Case Class with a companion Object that does the apply().

qbeast-spark/src/main/scala/io/qbeast/spark/internal/QbeastOptions.scala

Lines 42 to 49 in 2fedabc

	case class QbeastOptions(
	columnsToIndex: Seq[String],
	cubeSize: Int,
	stats: Option[DataFrame],
	txnAppId: Option[String],
	txnVersion: Option[String],
	userMetadata: Option[String])

We wanted to avoid having "default" fields in the case class, but then we end up having an empty object containing exactly those values.

qbeast-spark/src/main/scala/io/qbeast/spark/internal/QbeastOptions.scala

Lines 144 to 145 in 2fedabc

	lazy val empty: QbeastOptions =
	QbeastOptions(Seq.empty, DEFAULT_CUBE_SIZE, None, None, None, None)

This issue is to evaluate the creation of QbeastOptions following a Builder Pattern (like in Java) for Scala. Here's a practical guide: https://www.baeldung.com/scala/builder-pattern