[v638][core] Generalize TROOT::GetSharedLibDir() also on Windows #28425

Job	Run time
Windows 10 x86 Release	1h 39m 51s
Upload Event Payload	3s
Windows 10 x64 Release	1h 54m 58s
mac26 ARM64	31m 33s
fedora42 CMAKE_CXX_STANDARD=23	43m 53s
mac-beta ARM64	53m 20s
alma10	35m 2s
alma9 march_native CMAKE_BUILD_TYPE=RelWithDebInfo, CMAKE_CXX_FLAGS=-march=native, CMAKE_C_FLAGS=-march=native, builtin_zlib=ON, builtin_zstd=ON	30m 6s
mac15 ARM64 CMAKE_CXX_STANDARD=23	29m 30s
fedora43	36m 34s
alma9 modules_off runtime_cxxmodules=Off	29m 29s
mac14 X64 CMAKE_CXX_STANDARD=20	1h 2m 20s
alma9 CMAKE_BUILD_TYPE=Debug	1h 51m 55s
alma10 arm64 CMAKE_BUILD_TYPE=RelWithDebInfo, builtin_zlib=ON, builtin_zstd=ON	51m 59s
ubuntu2404 CMAKE_BUILD_TYPE=Debug	1h 37m 9s
alma8	34m 36s
ubuntu2510	35m 0s
alma10 clang Ninja CMAKE_C_COMPILER=clang, CMAKE_CXX_COMPILER=clang++	38m 56s
ubuntu22 imt=Off, CMAKE_BUILD_TYPE=Debug	1h 19m 35s
debian13 dev=ON, CMAKE_CXX_FLAGS=-Wsuggest-override	34m 1s
	17h 29m 50s

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