Some style settings can not be modified on Editor Utility Checkbox widget

Some style settings cannot be modified on the Editor variant of the checkbox widget (EditorUtilityCheckbox). This looks to be related to the style settings applied in FStarshipCoreStyle::SetupCheckboxStyles. Style settings set to FSlateNoResource work as expected, while settings with a brush specified cannot be modified in the editor.

Some changes were made in [Link Removed] to break the utility widgets out into their own classes, though this appears to have been broken (in a slightly different way) even before that change as a result of applying editor styles in the constructor.

1. Create a new Editor Utility Widget
2. Add an Editor Utility Checkbox
3. Attempt to change the Unchecked Image. Note that it works as expected
4. Attempt to change the Checked Image. Note that it does not update