Implement Extended JSON functionality required for FLE

2020-01-30: Updated target date of 2020-02-14 (4 weeks) Most work to implement extended JSON for FLE complete, with exception handling remaining. 2020-01-13: Initial target date of 2020-01-30 (2 weeks) Prioritized work on extended JSON now that we have uncovered it is a pre-requisite for FLE. Target date only encompasses the minimum required work to unblock FLE. Once this minimum required work is done, the project will pause and we will revisit this epic after 4.4.