introduce sct and remove metadata collection from ct

The idea here is to introduces sct as a ct-scan and make ct fast by removes metadata collection and save option from it. This is in line the user feedback that ct should not be seen as scan but as beamline-snapshot

sct instead will be collecting metadata and will come with save=true by default.

(for those who follow the bliss dev chat: this merge request will not affect scan numbering!)