Import assets from manifest

Problem/Motivation

Right now the module only replaces library definitions with the ones defined in [module].foxy.yml and this only works with JS entry points.

Proposed resolution

The vite module recently committed work that maps stylesheets from the vite manifest 🐛 Styles imported in a chunk not being added to library RTBC . Let's borrow some of that without making vite a dependency of this module, and extend it to include assets.