[x] handle the 3 orderings options with CMake and add history and upgrade helper entries
[x] make sure version info, soversion info integral types/am/deriv components, orderings get passed through to libint2-config.cmake, config.h, configuration.cc, features
[x] add skeleton of the full cmake structure: generate->export->library. No source files compiled yet, but options are handed through and configure_files are in place. rm -rf build/ && cmake -S. -Bbuild && cmake --build build completes so libint2-config.cmake and other files in previous bullet can be inspected
configuration.cc (for libtool) and configuration.cc.cmake.in (for cmake) are duplicated at the moment
currently atop #309 . here's the diff of the new stuff: https://github.com/loriab/libint/compare/intconfig...loriab:libint:orderingsconfig
configure_files are in place.rm -rf build/ && cmake -S. -Bbuild && cmake --build buildcompletes solibint2-config.cmakeand other files in previous bullet can be inspectedconfiguration.cc(for libtool) andconfiguration.cc.cmake.in(for cmake) are duplicated at the moment