region displays the default region of Apple Account logged into the MAS.

If you change the region of the MAS to be different than the default region of the logged in Apple Account, region will still display the default region of the Apple Account, rather than the region configured in the MAS.

If you use a different Apple Account in the MAS than for your macOS user, region will display the default region for the MAS Apple Account.

See initial info from #689 (comment).

Additional tests were done to determine the rest of the info here.

Either always output the MAS region, or reword the region docs to be correct (& later try to fix region to output the MAS region.