Keep track of created orders in the auto mode.

[air2]

Because of bug https://github.com/letsencrypt/boulder/issues/3335, it is recommended to let clients keep track of orders. However currently the orders generated in the auto mode cannot be tracked. A simple callback in the options for the auto certificate registration could solve this. After creating the order something like:

if (opts.createdOrderCallbackFn) {
    try {

        await opts.createdOrderCallbackFn(order);
    } catch (error) {
        log(`[auto] createdOrderCallbackFn threw error: ${getAsError(error).message}`);
        throw error
    }
}

Could let the caller notify of the created order and store it as liked. I am relative new to Let's Encrypt and the Acme protocol. So maybe this idea is just not the way to go. Can somebody with more experience shine a light on this?

I could of course create a pull request for this.