PySpark statistical criteria implementation  #19

In order to extend the ambrosia functionality for working with spark data to an acceptable level, it is necessary to implement a set of PySpark statistical criteria classes at ambrosia.spark_tools.stat_criteria

• Independent T-test
• Relative T-test
• MannWhitney test
• Wilcoxon test
• Bootstrap criterion (+relative sampling functionality)
• Shapiro-Wilk test