Support dynamic import

[mstoykov]

Feature Description

Support dynamic import

In part to have the same support as we have for require which ... basically has the same functionality and so that people don't have to mix require and ESM syntax in case they want to load some modules in a more dynamic matter

Suggested Solution (optional)

This was skipped in #3456 as it wasn't necessary and also as a lot of it usability depends on #3858.

This doesn't change anything about https://github.com/grafana/k6/issues/3020

Already existing or connected issues / PRs (optional)

#3858 will be needed for better UX https://github.com/grafana/k6/issues/3020 - might be a thing we can tackle at the same time too