wip: add id and key to experiement core

Author: muzahidul-opti

Sources/Data Model/ExperimentCore.swift

@@ -18,6 +18,8 @@ import Foundation
 
 
 protocol ExperimentCore: OptimizelyExperiment {
+    var id: String { get }
+    var key: String { get }
     var audiences: String { get set }
     var layerId: String { get }
     var variations: [Variation] { get }