full cmake 4/N: remainder of config.h

[loriab]

currently atop #312 . diff of the new stuff: loriab/libint@orderingsconfig...loriab:libint:configconfig

• remaining configure.ac options that feed config.h transferred to cmake, except for dependency options. largely tested to replicate libtool and added to upgrade guide.
• LIBINT_HOST_ARCH & LIBINT_TARGET_ARCH removed as never used
• CXX_ALLOWS_DEFPARAMTEMPLATE_AS_TEMPTEMPPARAM left undef as there's no libtool check. are cxx_template_template_parameters (c++98) or cxx_default_function_template_args (c++11) relevant from https://cmake.org/cmake/help/v3.26/prop_gbl/CMAKE_CXX_KNOWN_FEATURES.html ?
• the LIBINT2_REALTYPE/LIBINT_USER_DEFINED_REAL have a compile-check, and the data transfer seems to hold together, but definitely needs testing with full code. it's only for the C interface?