Fix format_to + FMT_STRING for wide character type #6013

Job	Run time
mingw (mingw64)	3m 44s
mingw (ucrt64)	3m 48s
build (windows-2019, Win32, v142, 17, Debug)	2m 2s
build (windows-2019, Win32, v142, 17, Release)	2m 38s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	2m 10s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	1m 50s
build (windows-2019, x64, v140, 14, Debug)	1m 7s
build (windows-2019, x64, v140, 14, Release)	1m 47s
build (windows-2019, x64, v141, 17, Debug)	1m 20s
build (windows-2019, x64, v141, 17, Release)	2m 15s
build (windows-2019, x64, v142, 17, Debug)	1m 16s
build (windows-2019, x64, v142, 17, Release)	2m 11s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 3s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 7s
build (windows-2019, x64, v142, 20, Debug)	1m 44s
build (windows-2019, x64, v142, 20, Release)	3m 4s
build (windows-2022, x64, v143, Debug, 20)	1m 57s
	36m 3s

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