Export shader-composer unit for working with DietSprite

[gsimone]

import { DietSpriteUnit } from 'diet-sprite/sc'
import { useDietSprite } from 'diet-sprite/r3f'

...
const texture = useTexture(...)
const [geometry, dataTexture] = useDietSprite(...)

...
position: DietSpriteUnit( VertexID, dataTexture ),
color: FlipbookUnit( texture, [5, 5], 30 ) // texture, slices, fps 
...