update rollup from 2.35.1 (2020-12-14) to at least 3.16.0 (2023-02-17), or ideally latest (4.6.1, 2023-11-30)

Splitting this off as a new issue so it can be tracked more easily. See the original issue for more context:

> `output.sourcemapIgnoreList` was added to `rollup` in `3.16.0` (`2023-02-17`):
>
> - https://github.com/rollup/rollup/blob/master/CHANGELOG.md#3160
> - > Support `output.sourcemapIgnoreList` option to mark file sources as ignored in the `x_google_ignoreList` attribute of the resulting sourcemap (rollup/rollup#4848)
>
> `microbundle` is using a super outdated version of `rollup` (`2.35.1`) from `2020-12-14`:
>
> - https://github.com/developit/microbundle/blob/c76c41f8317611f7592d8e44c569e8083076f25f/package.json#L102
>
> So before we can implement this change, we'll need to upgrade to a modern version of `rollup`.
>
> _Originally posted by @0xdevalias in https://github.com/developit/microbundle/issues/1066#issuecomment-1837821773_

`microbundle` is currently using `rollup` `2.35.1` (`2020-12-14`):

- https://github.com/rollup/rollup/blob/master/CHANGELOG.md#2351

`output.sourcemapIgnoreList` (required to implement #1066) support was added in `3.16.0` (`2023-02-17`):

- https://github.com/rollup/rollup/blob/master/CHANGELOG.md#3160

Latest version (at time of writing) is `4.6.1` (`2023-11-30`):

- https://github.com/rollup/rollup/blob/master/CHANGELOG.md#461