LibWeb: Move SVGPathElement methods into SVGGeometryElement

From the spec:

> Interface SVGGeometryElement represents SVG elements whose rendering
> is defined by geometry with an equivalent path, and which can be
> filled and stroked. This includes paths and the basic shapes.

- https://svgwg.org/svg2-draft/types.html#InterfaceSVGGeometryElement

Making them all create an SVGPathBox, and return a Path from get_path(),
means we can implement the "basic shapes" using the path system we
already have. :^)

Userland/Libraries/LibWeb/SVG/SVGPathElement.h

@@ -89,11 +89,9 @@ public:
     SVGPathElement(DOM::Document&, QualifiedName);
     virtual ~SVGPathElement() override = default;
 
-    virtual RefPtr<Layout::Node> create_layout_node(NonnullRefPtr<CSS::StyleProperties>) override;
-
     virtual void parse_attribute(const FlyString& name, const String& value) override;
 
-    Gfx::Path& get_path();
+    virtual Gfx::Path& get_path() override;
 
 private:
     Vector<PathInstruction> m_instructions;