Add draft for binary switch based on separate module

[s1ck]

Adds an additional module spark-cypher-morpheus that depends on spark-graph-api.

Main trait is defined as follows:

private[morpheus] class MorpheusSession(override val sparkSession: SparkSession) extends RelationalCypherSession[DataFrameTable] with org.apache.spark.graph.api.CypherSession

See GraphApp for usage example and switching between APIs

Pros:

• user only needs to switch from SparkCypherSession.create to MorpheusSession.create

Cons:

• CAPSSession needs to be in implicit scope for PGDS implementations (maybe SparkSession is enough here?)

Needs apache/spark#24297 installed locally to compile and run.