layout: Make geom.rs logical geoemetry types more ergonomic (#32633)

Make using the logical geometry types more ergonomic by having them all
implement `Copy` (at most 4 64-bit numbers), similar to what `euclid`
does. In addition add an implementation of `Neg` for `LogicalVec` and
`LogicalSides` as it will be used in upcoming table implementation code.

components/layout_2020/flexbox/layout.rs

@@ -428,7 +428,7 @@ impl FlexContainer {
                     },
                 };
                 for (fragment, _) in &mut line.item_fragments {
-                    fragment.content_rect.start_corner += &flow_relative_line_position
+                    fragment.content_rect.start_corner += flow_relative_line_position
                 }
                 line.item_fragments
             });