Update after native ESM support

[mstoykov]

What?

Update after ESM is now natively supported.

Checklist

• I have used a meaningful title for the PR.
• I have described the changes I've made in the "What?" section above.
• I have performed a self-review of my changes.
• I have run the npm start command locally and verified that the changes look good.

• I have made my changes in the docs/sources/next folder of the documentation.
• I have reflected my changes in the docs/sources/v{most_recent_release} folder of the documentation.
• I have reflected my changes in the relevant folders of the two previous k6 versions of the documentation (if still applicable to previous versions).

• I have made my changes in the docs/sources/next folder of the documentation.

Related PR(s)/Issue(s)

[ppcano]

LGTM, I share some thoughts for later consideration:

1 - The guides are versioned, so I am unsure if it is desired to mention specific version changes After v0.53.0....
On the other hand, it may be desired b/c users tend to read the latest version. This is why we decided time ago to remove these references after two releases.

2 - --compatibility-mode=base is now a very rare case. I think we could drop the documentation about this option, and leave the versioned docs for older references.

3 - About --compatibility-mode=experimental_enhanced. I shared this before and don't know exactly the future plan, but we could rename this option to just typescript... or mode=typescript