Migrate billboard to bit-ecs

[keianhzo]

This PR migrates the billboard component and also makes some choices that I'd like comments on:

• Adds a inflatorWrapper function to wrap a component inflator. I assume we will need to do this quite a lot for some components so it might be useful to have a convenience function for it
• I found myself using the default inflator in a few places so I thought that it might make sense to reuse the same one. As we add more it might make sense to expose them in an object
• Exposes the main camera in App. I think we are accessing to this through the scene in a few places so I thought it might make sense to expose it here

[netpro2k]

Looking good. Made a few small comments.

Biggest one would be getting rid of use of frame scheduler, I suspect we won't need that anymore going forward but maybe we will want some utility functions for doing something similar if we find ourselves writing the same code in many systems.

Also lets make sure we preserver that TODO, billboard as it is kind of stopped making sense since we now have many potential cameras in the scene. (Maybe it just needs to be renamed face-player. I would definitely like to also explore something more akin to how other engines handle billboarding and have it be more of a rendering concept, sitting at the same level as something like Mesh. That allows us to do the billboarding as part of the vertex shader.

[keianhzo]

Thanks for the feedback, it helped a lot. Regarding the vertex shader approach, definitely worth exploring specially if lookAt is as expensive as you mentioned. We still would need it for non-mesh objects but it would save some CPU for geometries.

I have addressed most of the feedback except from:

• I have kept the inflatorWrapper. I think the amount of code that we are adding < amount of code that we are removing and could be handy for other simple components.
• As inView ended up being just a function call after the refactor, I have left onlyY as a boolean.