Implement list tool command.

This commit implements the `list tool` command.

The command is responsible for displaying a list of install global tools.

Fixes #8548.

test/dotnet-list-reference.Tests/GivenDotnetListReference.cs

@@ -33,6 +33,7 @@ Options:
 
 Commands:
   reference   .NET Core Project-to-Project dependency viewer
+  tool        Lists installed tools in the current development environment.
 ";
 
         const string FrameworkNet451Arg = "-f net451";