[FEATURE] Provide an interface for users to implement custom rule types that can be integrated with spark-expectations

[phanikumarvemuri]

Is your feature request related to a problem? Please describe. As of now spark-expectations support row_dq, agg_dq and query_dq rule types. If users want to add their own rule types for example running data quality rules on subset of data using windowing functions SE should provide a way for users to integrate such rule types

Describe the solution you'd like TBD