Add a feature to resolve dependencies for Bundle API

When using the bundle API, we may import CSS from third-party dependencies with @import.

e.g.

// style.css

@import "./common.css";
@import "bootstrap/dist/css/bootstrap.min.css"

// ...

Avoid the overhead of passing functions to Rust, we can add a parsing dependency entry point configuration (maybe projectRoot or new config ).

An example of parse the path:

  const resolve = require("enhanced-resolve");

  resolve(projectRoot, "bootstrap/dist/css/bootstrap.min.css"

( we can use libraries like parcel-resolver or rspack-resolver )

Related to #747 , https://github.com/fz6m/lightningcss-loader/issues/8#issuecomment-2643318025

Start by locating the Bundle API entry point and reviewing how the proposed projectRoot or parsing dependency entry-point configuration would reach CSS @import handling. Compare the suggested enhanced-resolve, parcel-resolver, and rspack-resolver approaches; done means third-party dependency imports such as bootstrap/dist/css/bootstrap.min.css resolve through the Bundle API without passing functions to Rust.