reorder data axes to RAS before passing onto Napari. This avoids
potential issues in affine handling:
napari/napari#3410

We also now drop the non-diagonal (rotation, shear) components from the
affine, since napari does not currently handle these.

oi

patient left will be to the right side of the screen
(radiological orientation)

verified that for each dimensions, moving the slider to the right moves
to S, P or L as expected, depending on the visible dimensions

update reorder_axes to take a specified target orientation instead of assuming RAS
Use LPS rather than SPL for now so that affine_plumb[:3, :3] will be diagonal.
Once appropriate fixes for perfmuted axes have been made to napari, we can switch to SPL

Co-authored-by: Christopher Nauroth-Kreß <56394171+ch-n@users.noreply.github.com>

use as_reoriented method as it is more concise and will also update the affine we pass on in the metadata

Co-authored-by: Christopher Nauroth-Kreß <56394171+ch-n@users.noreply.github.com>