The newer UCRT runtime has native support for UTF-8, including forcing
it as the active codepage even before `main()` is called. This means
the c runtime will properly convert windows WCHAR:s into UTF-8 bytes,
as early as the argv/argc params to `main()` . Whereas MSVCRT does not
support this reliably and required us to use `wmain()`.
Only MSVC supports using manifest files directly as source files.
The solution for other Windows toolchains is to use a .rc file.
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