In-app vault export support (#729)

* First pass at vault export UI

* Password validation via cryptoService

* Export service framework

* support for constructing json export data

* Support for constructing csv export data

* Cleanup and simplification

* Completion of vault export feature

* Formatting and simplification

* Use dialog instead of toast for invalid master password entry

src/Core/Models/Export/FolderWithId.cs

@@ -0,0 +1,16 @@
+using Bit.Core.Models.View;
+using Newtonsoft.Json;
+
+namespace Bit.Core.Models.Export
+{
+    public class FolderWithId : Folder
+    {
+        public FolderWithId(FolderView obj) : base(obj)
+        {
+            Id = obj.Id;
+        }
+
+        [JsonProperty(Order = int.MinValue)]
+        public string Id { get; set; }
+    }
+}