Fix #580 by using a fixed-point implementation for unit conversions using integer representations #1936

Job	Run time
Generate build matrix for Conan CI	3s
fmtlib gsl-lite C++20 Apple Clang 15 Debug	1m 30s
fmtlib none C++20 Apple Clang 15 Release	52s
fmtlib gsl-lite C++20 Clang-16 (x86-64) Debug	1m 7s
fmtlib none C++20 Clang-16 (x86-64) Release	1m 3s
fmtlib none C++20 Clang-17 (x86-64) Debug	10m 24s
std::format gsl-lite C++20 Clang-17 (x86-64) Debug	9m 38s
std::format gsl-lite C++20 Clang-18 (arm64) Debug	8m 5s
fmtlib none C++23 Clang-18 (arm64) Release	7m 5s
std::format gsl-lite C++20 Clang-18 (x86-64) Debug	11m 17s
std::format none C++23 Clang-18 (x86-64) Debug	10m 49s
fmtlib gsl-lite C++20 GCC-12 Debug	4m 31s
fmtlib ms-gsl C++20 GCC-12 Release	4m 54s
fmtlib ms-gsl C++23 GCC-12 Debug	4m 40s
std::format gsl-lite C++20 GCC-13 Debug	6m 7s
std::format none C++20 GCC-13 Release	6m 8s
fmtlib none C++20 GCC-14 Release	6m 48s
std::format gsl-lite C++20 GCC-14 Debug	5m 28s
fmtlib gsl-lite C++20 MSVC 14.4 Debug	1m 28s
std::format gsl-lite C++20 MSVC 14.4 Debug	1m 32s
Promote Conan package	0s
	1h 43m 29s

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