Nothing extra is needed to use Rollup with gulp, so this refactors the
recipe to use Rollup's JavaScript API directly.

It seems too basic and obvious.

It should be very obvious that you can `require` functions from other
files in `gulpfile.js` and export them as tasks, it seems unnecessary to
use `gulp-hub`.

The `cwd` option is described in the docs for `gulp.src`, and `--cwd`
can be found when running `gulp --help`. Having this as a recipe seems
unnecessary.

gulp v4 supports this natively now, tasks can return a child process.

https://gulpjs.com/docs/en/getting-started/async-completion#returning-a-child-process

This is a core feature, it's not necessary to explain it in a recipe.

gulp v4 supports this natively, as explained in the recipe itself, so
there is no need for it.

gulp v4 supports this natively by combining `since` with
`gulp.lastRun()`.

https://gulpjs.com/docs/en/api/lastrun

Co-authored-by: Blaine Bublitz <blaine.bublitz@gmail.com>

Rollup is imported by name, so it should be called like `rollup()`.

Fix: Bind src/dest/symlink to the gulp instance to support esm exports (ref standard-things/esm#797)