SecureString is not boud as ArgumentType

[lennybacon]

It would be great to have the ability to use SecureString as argument type.

      var argument = new Argument("password") {
        Description = "The user name for basic authentication.",
        ArgumentType = typeof(SecureString),
        Arity = ArgumentArity.ZeroOrOne
      };

[jonsequitur]

SecureString should be avoided: https://docs.microsoft.com/en-us/dotnet/api/system.security.securestring?view=net-5.0#remarks

It's on the path to obsoletion (dotnet/designs#147), so we shouldn't add support for it here.

[lennybacon]

Thanks