FieldArray should have a beforeSubmit prop

### Are you submitting a **bug report** or a **feature request**?
Feature Request

### What is the current behavior?
Field Arrays don't make use of "beforeSubmit" as regular Fields do.
Perhaps it was left out intentionally, but I would expect Field Arrays to accept most, if not all, of the same props as a regular Field.

### What is the expected behavior?
Field Arrays would employ "beforeSubmit"

### Sandbox Link

### What's your environment?

### Other information
I may try and resolve this myself one day but as stated above, I just don't know if there was a very good reason for leaving this out in the first place.