LibGfx: Unify Rect, Point, and Size

This commit unifies methods and method/param names between the above
classes, as well as adds [[nodiscard]] and ALWAYS_INLINE where
appropriate. It also renamed the various move_by methods to
translate_by, as that more closely matches the transformation
terminology.

Userland/Libraries/LibWeb/Layout/InlineFormattingContext.cpp

@@ -154,7 +154,7 @@ void InlineFormattingContext::run(Box&, LayoutMode layout_mode)
                 // Shift subsequent sibling fragments to the right to adjust for change in width.
                 for (size_t j = i + 1; j < line_box.fragments().size(); ++j) {
                     auto offset = line_box.fragments()[j].offset();
-                    offset.move_by(diff, 0);
+                    offset.translate_by(diff, 0);
                     line_box.fragments()[j].set_offset(offset);
                 }
             }