configs: Update scripts and spec file with layout changes
    
    With the configs in the new place, update the scripts to find
    them and utilize the base-generic and generic heirarchy to apply
    configs and overrides.
    
    Implement new process_configs.sh script that post-process the
    config changes in a simple script and remove those commands
    from the spec file.  Add option flags to preserve functionality.
    
    config_generation is a simple rename of baseconfig -> generic and
    debugconfig -> debug and arm64 -> aarach64.
    
    build_configs.sh is modified to find configs in generic and base-generic and
    then apply base-generic first and if any generic files, apply those next.  The
    generic directory is used as an overrides and is expected to be empty for
    Fedora initially.
    
    kernel.spec is modified to use process_configs.sh instead of all the
    commands in the spec file.  Enabled spec options are translated to
    script options.  The config manipulation is moved to be grouped
    with all config manipulation commands.  This makes 'cd configs/' simpler.
    Now all config scripts and executiion are done in configs/ directory.
    
    v1 -> v2:
    * the scripts were not working with SUBARCH correctly
    * checkoptions was using wrong comparison file
    * passing wrong kernel version to process_configs in spec file
    
    v2 -> v3:
    (incorporate Laura A's feedback)
    * update README.txt
    * fix build_configs.sh warnings
    * Output info message on listnewconfig failure