Creates an alias for a directory and assigns the alias to the directory. The alias is used to construct the access URL for the directory, such as http://<alias>.awsapps.com.
After an alias has been created, it cannot be deleted or reused, so this operation should only be used when absolutely necessary.
/// A client exception has occurred.
///
/// The specified entity already exists.
///
/// The specified entity could not be found.
///
/// One or more parameters are not valid.
///
/// An exception has occurred in AWS Directory Service.
///