Rename "Microsoft Personal" account type to "Microsoft"

Making up our own custom names for different account types is causing additional confusion, not reducing it. Fixes #305 (closed)

I had originally intended this change for GNOME 47 because it breaks string freeze; however, I notice that the "Microsoft" account type was renamed to "Microsoft Personal" only in GNOME 46. It would probably be best to backtrack on this naming sooner rather than later. I can request a string freeze exception for this if you agree with backporting to 46.