This adds a new dependency on peniko, reintroduces kurbo for geometry (!), removes the now defunct types from piet-scene and updates all the test scenes to use the new types.
This lets us use https://github.com/wgsl-analyzer/wgsl-analyzer for writing the wgsl files.
The imports (for wgsl-analyzer) have to be machine specific at the moment - to use this you need to configure .vscode/settings.json yourself. The alternative is to point them at static files on GitHub, which is tempting to make things easier, but would potentially go out of sync with what is actually used.
Starting an experimental port to WGSL shader language, using wgpu to run the examples. As of this commit, it's quite hacky and takes some shortcuts, but does render paths to a grayscale texture.
