bugfix/use-data.data-in-open_scene

[psobolewskiPhD]

Description

If a single scene image is opened, the return is data.data which is just the array from the xarray.DataArray
If a multi scene file is opened (using the scene selector widget) the return from the open_scene is an image layer with data, the actual xarray.DataArray.

Napari actually handles this just fine, but some downstream plugins do not, expecting numpy arrays (e.g. napari-matplotlib). This is sort of something they should be better at handling, perhaps using np.asarray, but at the same time I feel like these two should work the same?
I think this plugin should/could be the default beyond builtins, so probably standardizing on the array and not xarray.DataArray is best, so probably data.data is preferred as a default behavior.
As the person partially responsible for the scene selector, I think this was an oversight on my part...

So in this PR I just make that small change and update the test accordingly.
At the same time, I can understand just returning the xarray.DataArray. But then for consistency, the single scene should just return data.

Pull request recommendations:

• Name your pull request your-development-type/short-description. Ex: feature/read-tiff-files
• Link to any relevant issue in the PR description. Ex: Resolves [admin/build-py39 #12], adds tiff file format support
• Provide context of changes.
• Provide relevant tests for your feature or bug fix: I updated the test for the change.
• Provide or update documentation for any feature added by your pull request.

Thanks for contributing!

[psobolewskiPhD]

Lint CI fail is unrelated, hopefully fixed by #70

[evamaxfield]

Seems fine to me! Thanks! Also @psobolewskiPhD do you mind if I give you write access to this repo?

I unfortunately haven't had time to work on imaging / cell science stuff in a long time. Happy to still review but I don't see myself as a large code author for the foreseeable future...

[evamaxfield]

Reason being: if you have write access you can publish releases after something merges.

[psobolewskiPhD]

Um, I don't mind I guess, if you think it's helpful!
I'll definitely need to bone up on releases and all that—I've never done that.