[CMake] Move towards target-based CMake and partly fix picking up headers from an installed ROOT #15896

Job	Run time
Windows 10 x64 Release	2h 9m 4s
Windows 10 x86 Release	1h 0m 13s
mac13 ARM64 LLVM_ENABLE_ASSERTIONS=On, builtin_zlib=ON	25m 45s
mac14 X64 LLVM_ENABLE_ASSERTIONS=On, CMAKE_CXX_STANDARD=20	1h 7m 44s
mac15 ARM64 LLVM_ENABLE_ASSERTIONS=On, CMAKE_CXX_STANDARD=20	34m 4s
Upload Event Payload	3s
mac-beta ARM64 LLVM_ENABLE_ASSERTIONS=On, CMAKE_CXX_STANDARD=20	47m 42s
fedora40 LLVM_ENABLE_ASSERTIONS=On, CMAKE_CXX_STANDARD=20	1h 25m 13s
fedora41 LLVM_ENABLE_ASSERTIONS=On	43m 37s
alma8 LLVM_ENABLE_ASSERTIONS=On	46m 21s
alma9 LLVM_ENABLE_ASSERTIONS=On, CMAKE_BUILD_TYPE=Debug	1h 21m 36s
ubuntu22 imt=Off, LLVM_ENABLE_ASSERTIONS=On, CMAKE_BUILD_TYPE=Debug	1h 58m 44s
ubuntu2404 LLVM_ENABLE_ASSERTIONS=On, CMAKE_BUILD_TYPE=Debug	2h 15m 1s
ubuntu2410 LLVM_ENABLE_ASSERTIONS=On, CMAKE_BUILD_TYPE=Debug	2h 12m 37s
debian125 LLVM_ENABLE_ASSERTIONS=On, CMAKE_CXX_STANDARD=20	1h 5m 11s
alma9 modules_off runtime_cxxmodules=Off	1h 7m 52s
alma9 march_native CMAKE_BUILD_TYPE=RelWithDebInfo, CMAKE_CXX_FLAGS=-march=native, CMAKE_C_FLAGS=-march=native, fortran=OFF	43m 11s
alma9 arm64 CMAKE_BUILD_TYPE=RelWithDebInfo	44m 32s
alma9-clang clang LLVM_ENABLE_ASSERTIONS=On, CMAKE_C_COMPILER=clang, CMAKE_CXX_COMPILER=clang++	52m 4s
	21h 20m 34s

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