This exposes significantly more of the previously internal encoding guts.
This is beneficial for its own sake as there always seem to be new and interesting things that are supported by the encoding and GPU pipeline that are not directly exposed by the scene builder.
The secondary purpose is laying the groundwork for scene *de*coding and processing. This will enable us to implement various stages of the pipeline on the CPU.
* Move the vello crate to the root of the crate
* Add warning that README is work in progress
* Add newline in warning
* Move the unlicense into the shader folder
* Fixup wgsl-analyzer include paths
