Warn the user if they are leaving a story edit page with unsaved changes

**Branch/Commit:**

Main branch

**Describe the feature:**

It would be nice to be warned that you have unsaved changes if you are going back/clicking a link/closing the tab, so a click somewhere by mistake does not clear whatever was being done.

**Problem:**

Currently, if you click in the wrong place or press the wrong key combination to leave the current page, you can lose information that was not saved.

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