Use Dataset.from_images in wkcuber and wk upload

[jstriebel]

Detailed Description

Since Dataset.from images is now capable of most standard wkcuber features (after #820) and has some improvements, we should use it in the wkcuber CLI (might also be a webknossos-lib CLI itself, reexported in wkcuber), and use this for the webknossos upload conversion.

[philippotto]

I would suggest to start using Dataset.from_images as soon as possible and if an error occurs, fallback to the old conversion mechanism. That approach would unblock this issue, thus, allowing us to reap the benefits of the new API as well as having it tested by real-world data.