Ability to pass extra data during email signup

The [Javascript SDK]( provides the ability to send and attach metadata to an user during creation through the options.data field.

At the moment, the [EmailAuth]( doesn't provide the ability to do the same thing.

I was wondering if you would considering adding a prop that can be used to pass through metadata to that the signUp call.

If that sounds like a good idea to you, I'm happy to give it a try and submit a PR.