[FEATURE]: dimension attribute are lost when stacking an xarray

[lanougue]

Is your feature request related to a problem?

No

Describe the solution you'd like

Hi all, when stacking an array my_xarray.stack(multi=('x','y')), the attributes of stacked dimension (x and y in the example) are lost. It would be nice to keep them. It would also be nice to have them back when unstacking.
Thanks

Describe alternatives you've considered

No response

Additional context

No response

[keewis]

this is a side effect of how stack works at the moment: the coordinates which are being stacked are converted to MultiIndex levels, which are not actually variables and thus lose the attributes. The ongoing index refactor promotes MultiIndex levels to coordinates, which means the coordinates don't have to be dropped in the first place.

Have a look at #5692 if you're interested in the current progress.

[lanougue]

ok, thanks ! I will thus be patient