* Refactor postgresql_idx to simplify code
Have refactored the postgresql_idx module to:
* Use the class schema in the drop function rather than a passed in one
* Remove the if/else and just return the bool in the drop and create
functions
* Refactor postgresql_ext module
Have refactored the postgresql_ext module to:
* Remove an unused exception
* Simplify logic in the create and update functions
* Use list comprehension to simplify getting the available version
* Refactor postgresql_user_obj_stat_info module
Have refactored the postgresql_user_obj_stat_info module to:
* Simplify the logic in some of the functions
* Reduce duplicate code
* Add changelog fragment
