OrderSetAttribute implementation

OrderSets will be extended via attributes to associate cycle number, the total number of cycles in the regimen, and the length of the regimen cycles.

Please refer to this Talk post for more detail: https://talk.openmrs.org/t/chemotherapy-ordering-data-design/19133

Copy the green commits from here: https://github.com/idlewis/openmrs-core/commits/order_set_attributes