Fix format_to + FMT_STRING for wide character type #6008

Job	Run time
mingw (mingw64)	4m 12s
mingw (ucrt64)	4m 46s
build (windows-2019, Win32, v142, 17, Debug)	1m 30s
build (windows-2019, Win32, v142, 17, Release)	2m 24s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 23s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 50s
build (windows-2019, x64, v140, 14, Debug)	2m 18s
build (windows-2019, x64, v140, 14, Release)	2m 55s
build (windows-2019, x64, v141, 17, Debug)	2m 19s
build (windows-2019, x64, v141, 17, Release)	2m 11s
build (windows-2019, x64, v142, 17, Debug)	1m 8s
build (windows-2019, x64, v142, 17, Release)	2m 17s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 45s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	4m 0s
build (windows-2019, x64, v142, 20, Debug)	2m 5s
build (windows-2019, x64, v142, 20, Release)	2m 55s
build (windows-2022, x64, v143, Debug, 20)	2m 3s
	43m 1s

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