Update to v7.0.1 and switch to CMake build system
    
     - Updates the library to v7.0.1
     - Switches from autotools to CMake/ninja build system
     - Switches from pqxx.org source to GitHub source forge and uses forge RPM macros
     - Adds bcond's for running checks and building documentation
    
     * .gitignore: Update sources to v7.0.1
     * libpqxx-2.6.8-multilib.patch: Drop
     * libpqxx.spec: Updates to v7.0.1 and modernizes build
     * libpqxx_configure.patch: Drop
     * sources: Update sources to v7.0.1