Respect WidgetVisuals::expansion in TextEdit (#8013)

This broke in #7587

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Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/egui/src/widgets/text_edit/builder.rs

@@ -707,7 +707,11 @@ impl TextEdit<'_> {
                     .frame
                     .fill(background_color)
                     .corner_radius(corner_radius)
-                    .inner_margin(allocated.frame.inner_margin - Margin::same(stroke.width as i8))
+                    .inner_margin(
+                        allocated.frame.inner_margin
+                            + Margin::same((visuals.expansion - stroke.width).round() as i8),
+                    )
+                    .outer_margin(Margin::same(-(visuals.expansion as i8)))
                     .stroke(stroke)
             } else {
                 allocated.frame