When creating items, add confirmation before drawer is closed to prevent data loss

[bladey]

When you click the "Create " button and the side draw comes out, if you enter the fields then accidentally click on the overlayed background you lose everything you've entered.

Suggestion: If the create draw is open and any of the fields have been modified, and the user clicks on the background overlay there should be a confirmation "Are you sure you want to cancel?" Yes/No or along those lines.

Adapted from Keystone Community Slack - https://keystonejs.slack.com/archives/C01STDMEW3S/p1635902154448600