Create email alias

curl -X POST https://api.box.com/2.0/users/12345/email_aliases \
     -H 'Authorization: Bearer <ACCESS_TOKEN>'
     -H 'Content-Type: application/json" '
     -d '{
       "email": "alias@example.com"
     }'

BoxEmailAlias alias = await client.UsersManager
    .AddEmailAliasAsync(userId: "33333", email: "user+foo@example.com");

BoxUser user = new BoxUser(api, "0");
user.addEmailAlias("user+alias@example.com");

user_id = '33333'
user = client.user(user_id)
email_alias = user.add_email_alias('alias@example.com')

client.users.addEmailAlias('33333', 'user+baz@example.com')
    .then(alias => {
        /* alias -> {
            type: 'email_alias',
            id: '12345',
            is_confirmed: false,
            email: 'user+baz@example.com' }
        */
    });

client.users.createEmailAlias(
    userId: "33333",
    email: "user+alias@example.com"
) { (result: Result<EmailAlias, BoxSDKError>) in
    guard case let .success(alias) = result else {
        print("Error adding email alias")
        return
    }

    print("Added email alias \(alias.email) — user must confirm")
}