I tested this and this definitely compiles and these
changes were done programmatically but if there's still anything wrong
it shouldn't be hard to fix.
With this change it's going to be very easy to make further adjustments
to the calling conventions of all these external UEFI functions.
Closes#16309
There are still a few occurrences of "stage1" in the standard library
and self-hosted compiler source, however, these instances need a bit
more careful inspection to ensure no breakage.