8539: Allow alias in image cropper (#9266)

Co-authored-by: Owain Williams <owaingdwilliams@gmail.com>

src/Umbraco.Web/Editors/Binders/ContentModelBinderHelper.cs

@@ -1,5 +1,9 @@
-using System.Net;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
 using System.Net.Http;
+using System.Text;
+using System.Text.RegularExpressions;
 using System.Web.Http;
 using System.Web.Http.Controllers;
 using Umbraco.Core;
@@ -17,6 +21,8 @@ namespace Umbraco.Web.Editors.Binders
     /// </summary>
     internal static class ContentModelBinderHelper
     {
+        private const char _escapeChar = '\\';
+
         public static TModelSave BindModelFromMultipartRequest<TModelSave>(HttpActionContext actionContext, ModelBindingContext bindingContext)
             where TModelSave : IHaveUploadedFiles
         {
@@ -30,6 +36,7 @@ namespace Umbraco.Web.Editors.Binders
                 //The name that has been assigned in JS has 2 or more parts. The second part indicates the property id
                 // for which the file belongs, the remaining parts are just metadata that can be used by the property editor.
                 var parts = file.Headers.ContentDisposition.Name.Trim(Constants.CharArrays.DoubleQuote).Split(Constants.CharArrays.Underscore);
+
                 if (parts.Length < 2)
                 {
                     var response = actionContext.Request.CreateResponse(HttpStatusCode.BadRequest);