#2957 add formatting to date input on submit callback

[wlthomson]

Fixes #2957.

Change summary

Minor change, calls onUpdate callback after submitting date input. Ensures submitted values are formatted consistently and prevents error on submitting date without date picker.

Testing

Setup

• Create a new patient. Add a first and last name and date of birth. Press date of birth input field and press enter (triggers onSubmit callback).

Test cases

• Patient saves without error.

Related areas to think about

@joshxg knows this functionality best, so would be good to get some feedback just to check that this won't cause any unexpected side-effects?

[josh-griffin]