Add Javascript render parameters

[mmcarvalho]

Hi, great job on this package.
It would be very nice to support render configurations. Imagine this scenario: render the turnstile on a button click, but with appearance="interaction-only".
Since it takes a bit to act, a loading overlay is shown. If the challenge appears, currently there is no way to know it without listening to the DOM, so the loader can be removed.
If 'before-interactive-callback' would be supported, it would be a matter of configuring the callback.
Does this make sense or am I missing something out?
Thanks.