Port to ESM

GNOME Shell switched to ESM as part of 45 https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1499. This means all extensions will be broken unless ported.

See the GUADEC talk: https://youtu.be/qaZuQO0bK-M?t=21013

The official ones have already been ported https://gitlab.gnome.org/GNOME/gnome-shell-extensions/-/commit/a9114473751fd022a5208618a8c9bb488651a48a

The port, is not yet fully done. Docs will be out once it is done. (afaik)