Windows API systems without UTF-16 APIs

[glebm]

Currently the Windows build assumes that WriteConsoleW is available.

None of the Unicode stuff is actually available on Windows 98 (and similar API level systems such as the original Xbox).

Would you be OK with adding a build option to disable it? I can send a PR if so.
Is FMT_WINDOWS_HAS_UNICODE_APIS a good name for the build option?

Alternatively, perhaps we could add an option to disable the entire print subsystem (something like set(FMT_PRINT OFF))

[vitaut]

Windows 98 has been discontinued many years ago. Why should we care about supporting it? Is it for some kind of a retro computing project?

[glebm]

It'd be cool to have DevilutionX run on the original platform it launched on.
This is of course just for fun, it's not meant to be useful.

[glebm]

I've sent a PR in #3636. The change is tiny and it eliminates the need for us to maintain our own libfmt fork.