This makes it possible to run xtro consistently when not all platforms are
enabled.
Fixes https://github.com/xamarin/xamarin-macios/issues/12769.
Co-authored-by: GitHub Actions Autoformatter <github-actions-autoformatter@xamarin.com>
* Not every old annotations have been migrated (work in progress, to be completed in another PR);
* Sanitation of the data files (e.g. removal of dupes and fixed, by Apple, entries) is done, but not automated (also a work in progress)
Even then this is immediately useful, i.e. better merged before 15.6 gets branched.