Description of change

Did a pass at making the batcher generic. This is to set it up so that creating custom batchers becomes much easier. This will ultimatly take a few steps. This is the first one!

Essentially it removes the packAttributes / packIndex from the batchable objects and moves it to a batcher instead. This means we can create new batchers and modify the packAttribute function without having to modify any of the other batchable classes!

I also added a packQuadAttributes function to the batchers as this lets us batch the sprites even faster. Without this perf would be slower for spritesas we would need to copy sprite to a format packAttribute undertands and then copy that to the batch. packQuadAttributes does this in one step.

This is a draft for people to see where im at. Next steps will be:

• tie move geometry to custom batchers
• allow for new batchers to be registered
• work to remove the batchable objects and have them live on the sprite / mesh directly. This will make it much easier to customise batches as devs will only need to create a new batcher and then set the batch id on the sprite / mesh etc.
• auto generate the batching funcitions so users will just need to create a shader and make sure the required props live on the renderable and it will work magically :D This will be really cool!

Oh and as a bonus - bunny mark is running a bit faster now too.. so we will get some more perf wins! woop!

Pre-Merge Checklist

• Tests and/or benchmarks are included
• Documentation is changed or added
• Lint process passed (npm run lint)
• Tests passed (npm run test)