Allow options on LESS transform

[calculuschild]

LESS transform does not allow custom options such as "paths", which PACK supports for the other transforms.

i.e., from the README.md:

const run = async ()=>{
  const { bundle, render, ssr } = pack('./client/main.jsx', {
    libs : ['very_large_lib.js'], // Won't have transforms applied to it
    paths : ['./client/shared']   // option passed to Browserify
  });

However this ./.client/shared folder is not accessible to the LESS transform. Allows changing this:

await fs.outputFile('./build/homebrew/bundle.css', await lessTransform.generate());

to this:

await fs.outputFile('./build/homebrew/bundle.css', await lessTransform.generate({paths: './shared'}));