For both active and inactive raster mask, show the name of the raster which is used (or would be used) for the mask. This will allow tools like r.mask or GUI to do lower-level operations with or around mask without a need to know about defaults or user mechanism to change the name.

I'm repurposing the existing 'name' (full_name) key which is now always set (as opposed to being null when no mask is present) as the 'present' boolean key already has the information on the mask presence. I'm renaming full_name to name because that creates a simpler interface (which is whole point of outputting full name as opposed to two keys to get name and mapset).