added image preview to the file manager component

Oqtane.Shared/Models/File.cs

@@ -9,6 +9,8 @@ namespace Oqtane.Models
         public string Name { get; set; }
         public string Extension { get; set; }
         public int Size { get; set; }
+        public int ImageHeight { get; set; }
+        public int ImageWidth { get; set; }
 
         public string CreatedBy { get; set; }
         public DateTime CreatedOn { get; set; }