add types in the npm package output

[GrandSchtroumpf]

Currently @rive-app/canvas-advanced & @rive-app/webgl-advanced do not provide type definition.
Would be nice to include these types into the output folder & update the package.json.

Note: the OffscreenCanvas is not supported by Typescript by default anymore (see issue). You can either remove it or add a polyfill to avoid user compiler from breaking.

Thanks.

[zplata]

@GrandSchtroumpf We just merged support for types! I'd try with @rive-app/canvas-advanced over WebGL for best performance right now and support. And appreciate the tip about OffscreenCanvas, we included a types for that in this latest release 1.0.70!