common sw_engine: Implement ClipPath feature
Paint object can composite by using composite API.
ClipPath composite is clipping by path unit of paint.
The following cases are supported.
Shape->composite(Shape);
Scene->composite(Shape);
Picture->composite(Shape);
Add enum
enum CompMethod { None = 0, ClipPath };
Add APIs
Result composite(std::unique_ptr<Paint> comp, CompMethod method) const noexcept;
* Example: Added testClipPath
