Split the name input into first name and last name

[octopusinvitro]

See our contributing guides.

This is a business requirement because the supporter team wants to be able to separate them so that they can use "Dear blah" in Mailchimp templates.

For the id and name of the input, check names under autocomplete for given name and family name
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Input

[octopusinvitro]

This is on hold for now, until we need it for other cases.