This replaces most uses of the ""_format literal with function calls to
fmt::format(). The latter form is available in all versions of the fmt
library, while the ""_format literal is deprecated in version 8 and
removed in version 9.
This might cost us some performance and early error detection, because
in at least some versions of the fmt library the _format() construct was
used to compile the format patterns at run time. That's why there are
some uses of the literal left in places where performance might be more
critical, they need a closer look.
See #1704
It doesn't matter which function we use as long as we don't use the
return value from them. So the existing cases aren't a problem, but
this way this will not happen in the future where it might be a
problem.
