This PR adds a heart geo shape. ❤️
It also:
- adds `toSvgPathData` to geometry2d
- uses geometry2d in places where previously we recalculated things like
perimeter of ellipse
- flattens geo shape util components
- [x] Calculate the path length for the DashStyleHeart
### Change Type
- [x] `sdk` — Changes the tldraw SDK
- [x] `feature` — New feature
### Release Notes
- Adds a heart shape to the geo shape set.
