Add support for ESM

We are using basic scroll in our angular projects and it works great.

As angular has recently switched to an ESM based build using Vite, we get some warnings when starting our application:

It would be great, if you could provide an export of your plugin as ESM version?

The issue names no files or tests. Start by inspecting the package's existing JavaScript build and export configuration, then verify that an ESM import works in an Angular/Vite project without the reported warnings. Done means an ESM distribution is available.

Written by the indexing model from the issue text.