allow some packages to be loaded from source

[kevinbarabash]

In particular we want to allow @khanacademy/wonder-blocks-* components to be loaded from the source index.js so that we can report coverage for source files across all wonder-blocks components when testing them.

We need to update vite-server so that it

• loads the source index.js files when loading /node_modules/@khanacademy/wonder-blocks-*.js
• handle requests for /node_modules/@khanacademy/wonder-blocks-*.js/**/*.js