[RFE] unbundled / preserveModules support

I quite like the design and speed of esbuild, but I found that when I use it with `bundle: false` it doesn't do what I would expect. The dependencies of entrypoints are not built unless they are also listed as entrypoints. Even if the deps are listed as entrypoints, the import paths are not adjusted so they won't work.

So it would be nice if esbuild `bundle: false` worked like rollup's [preserveModules](https://rollupjs.org/guide/en/#outputpreservemodules).

Start by comparing esbuild's `bundle: false` behavior with Rollup's `preserveModules` behavior described in the issue. Trace how entrypoint dependencies and import paths are handled, then define completion as preserving those modules while producing working adjusted imports.

Written by the indexing model from the issue text.