Add trailing slash for -o

Author: Forgind

src/Cli/Microsoft.TemplateEngine.Cli/Commands/SharedOptions.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.CommandLine;
+using System.CommandLine.Parsing;
 
 namespace Microsoft.TemplateEngine.Cli.Commands
 {
@@ -11,7 +12,23 @@ public static class SharedOptions
         {
             Description = SymbolStrings.Option_Output,
             Required = false,
-            Arity = new ArgumentArity(1, 1)
+            Arity = new ArgumentArity(1, 1),
+            CustomParser = (ArgumentResult argumentResult) =>
+            {
+                var input = argumentResult.Tokens[0]?.Value;
+                if (string.IsNullOrWhiteSpace(input))
+                {
+                    return null;
+                }
+                else if (Path.EndsInDirectorySeparator(input))
+                {
+                    return new FileInfo(input);
+                }
+                else
+                {
+                    return new FileInfo(input + Path.DirectorySeparatorChar);
+                }
+            }
         };
 
         public static Option<FileInfo> ProjectPathOption { get; } = new Option<FileInfo>("--project")