feat: pre-configured assets

Popular asset libraries (such as [Kenney's assets](https://kenney.nl/assets)) could be distributed directly as Fibbo components, through dedicated libraries. Name : Fasset ? (Fibbo + Asset, pronounced like Facet ?) This would enable such DX : ```bash npm install @fasset/kenney ``` ```ts import { CharacterA } from "@fasset/kenney" import { FCharacterControllerKV } from "@fibbojs/3d" ... const player = new CharacterA() player.addController(new FCharacterControllerKV()) ``` We should ensure tree-shaking will work, so only imported models are included in the final bundle.