Adopt Spark NLP start function in Python
Adopt Spark NLP start function in Python

- make Apache Spark 3.0.x default package
- add is_spark24 key
- add memory key
- make default package _2.12 as it will be on Spark 3.0.x

JohnSnowLabs/spark-nlp,JohnSnowLabs/spark-nlp,JohnSnowLabs/spark-nlp,JohnSnowLabs/spark-nlp