Fixes alignxc

Fixes alignxc

• Use use_image_no_saving to be sure it works with save=False (due to bliss 2.0 and blissdata)
• Fix tomo_config instead of tomo_detector which can be hidden depending on the way detector_axis is defined
• Plus added test coverage for alignxc

It would be good to merge that for the 2.6, because that's bug fixes.