Add support for placing, discontinuing and revising orders via REST

encountertransaction {
    ...,
    drugOrders: [
        // creates a new order
        { careSetting: "OUTPATIENT", frequency: ..., etc }
        
        // discontinues an existing order
        { action: "DISCONTINUE", existingUuid: "abc-123", orderReason: "concept-for-Adverse-Reaction" } // optional date also
        
        // note that you can also do this:
        { action: "DISCONTINUE", drug: "uuid-for-ampicillin-100mg", orderReason: "concept-for-Adverse-Reaction" }
        // if there is active Ampicillin 100mg order, it is stopped, if not, this still
        // creates a new DC order

        // revises an existing order
        { action: "REVISE", existingUuid: "abc-123", ... }
        // under the hood, this will fetch abc-123 and call cloneForRevision() on it
        // so you only need to specify revised properties here (though you are allowed
        // to specify all)
        // All API constraints must still be maintained or an error is thrown, e.g. you
        // cannot change the drug/concept while doing a revision; you must have an
        // existing order; etc.
    ]
}