Allow CLI UI language to be overridden by an environment variable

src/dotnet/Program.cs

@@ -198,6 +198,9 @@ namespace Microsoft.DotNet.Cli
             // by default, .NET Core doesn't have all code pages needed for Console apps.
             // see the .NET Core Notes in https://msdn.microsoft.com/en-us/library/system.diagnostics.process(v=vs.110).aspx
             Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+
+            // Honor UI language customization
+            UILanguageOverride.Setup();
         }
 
         internal static bool TryGetBuiltInCommand(string commandName, out BuiltInCommandMetadata builtInCommand)