Optimization, UI improvements, Run command

src/Core/FileTime.Core/Models/IElement.cs

@@ -4,5 +4,7 @@ namespace FileTime.Core.Models
     {
         bool IsSpecial { get; }
         string GetPrimaryAttributeText();
+        Task<string> GetContent(CancellationToken token = default);
+        Task<long> GetElementSize(CancellationToken token = default);
     }
 }