Allow no-throw behavior when command-line parser sees an unexpected option

parent #520 
This PR is aim to fix the parent issue #520 , which is only related to handling unexpected arguments. Defining an argument in test command is adding an expected argument, which is non-relevant to this issue. Moreover, handling expected argument is already implemented here:
https://github.com/aspnet/KRuntime/blob/allow-no-throw-on-unexpected-options/test/Microsoft.Framework.CommandLineUtils.Tests/CommandLineApplicationTests.cs#L32