naming coherence for cameras

[mockersf]

Just something that irked me for a while, but not sure if it's worthy of a breaking change...

Basically, it's renaming UiCameraBundle to CameraUiBundle, to be aligned with Camera2dBundle and Camera3dBundle

While at it I also changed a few internals const/strings to be coherent

Feel free to close, I can live with it...

[ambeeeeee]

I think the renaming is good for consistency reasons, especially the underscores in the consts.

[cart]

Yeah consistency is good. My rationale for them being different was:

1. I would prefer the XCamera naming convention (ex: UiCamera)
2. Rust doesn't allow type names to start with numbers (ex: 2dCamera is invalid)
3. The "preferred" XCamera is the "default", which we override when rust's rules get in our way

I'm cool with these changes though.