Consider adding an "active image layer properties" editor for dimensional metadata

[ctrueden]

From @elevans:

This make me feel like we should have an area in the side panel that reports what the current image dimensions are and if any labels are present. A user can go ahead and update dimension labels (which behind the scenes can use napari metadata scheme to update axis labels. I haven't really thought about this much but just a quick idea maybe?

Of course, napari should have its own way of editing axis metadata, but it doesn't even read the xarray metadata yet, so in the meantime, we could make it convenient for people who are using napari-imagej.