Refactored the cart service to add more telemetry

1. Added more telemetry around starting redis cache
2. Now if you don't specify redis cache address via command line
or environment variable, it will run with local cart (no redis).
This is useful for debugging purposes

src/cartservice/interfaces/ICartStore.cs

@@ -4,6 +4,8 @@ namespace cartservice.interfaces
 {
     internal interface ICartStore
     {
+        Task InitializeAsync();
+        
         Task AddItemAsync(string userId, string productId, int quantity);
         Task EmptyCartAsync(string userId);