Implement an API to fetch all conditions for a patient

Implement ConditionService.getConditionHistory(Patient patient) to fetch the all conditions for a patient, grouped by unique condition (concept or, for non-coded concepts, the unique uncoded condition string) and, within each condition, a reverse chronological list of condition entries for that condition.

NOTE: please share the proposed method signature on the dev list for quick review.

Tasks:
1. Introduce "Get Conditions" privilege and ensure the privilege for fetching active conditions for a patient.
2. Should only include the non-voided, latest revision for a condition.
3. Should also include conditions that have been ended.