TSFN callback queue behavior clarification

### Affected URL(s)

https://nodejs.org/api/n-api.html#asynchronous-thread-safe-function-calls

### Description of the problem

Does a TSFN call only one callback from its queue per iteration of the event loop or does it call *all* callbacks in the queue in one iteration? Or maybe there is there some other policy?

Perhaps this detail could be clarified in the docs?

Thanks!