Fix format_to + FMT_STRING for wide character type #6006

Job	Run time
build (windows-2019, Win32, v142, 17, Debug)	1m 19s
mingw (mingw64)	3m 53s
mingw (ucrt64)	4m 2s
build (windows-2019, Win32, v142, 17, Release)	3m 1s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 4s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 26s
build (windows-2019, x64, v140, 14, Debug)	1m 17s
build (windows-2019, x64, v140, 14, Release)	1m 51s
build (windows-2019, x64, v141, 17, Debug)	1m 15s
build (windows-2019, x64, v141, 17, Release)	2m 7s
build (windows-2019, x64, v142, 17, Debug)	1m 39s
build (windows-2019, x64, v142, 17, Release)	2m 26s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 20s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 4s
build (windows-2019, x64, v142, 20, Debug)	1m 29s
build (windows-2019, x64, v142, 20, Release)	2m 59s
build (windows-2022, x64, v143, Debug, 20)	1m 30s
	35m 42s

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