Site Editor: Connect "Review Changes" modal to Site Editor's back/exit button when there are unsaved changes

[supernovia]

What

If a user clicks the back button to exit the site editor while changes are unsaved, show the Review Changes modal.

Why

When a user has unsaved changes and clicks the site editor back button, they get a generic "Leave Site" warning. It is not obvious to them that they need to click Review Changes.

In our testing, a user clicked the back/exit button four times without realizing they needed to click "Review Changes" in the lower left corner.

How

If possible, connect the site editor's final back/exit button to the Review Changes modal when unsaved changes are present: