Add catch-all "extra debug" CMake option

[msimberg]

We've disabled many CMake options by default, even in debug mode, for performance. However, sometimes it's still useful to enable those debug options. Instead of needing to know which debug options to add, it may make sense to add a single catch-all CMake option that enables all the CMake options that may make sense for debugging. Since this option would really primarily be used for debugging we can be quite aggressive in turning on options that may have a big impact on performance. The individual CMake options should probably still stay so that they can be turned off individually if one knows that a particular check isn't useful in a situation. However, I think the default (with this CMake option) should be to turn as much checking as possible on so that a user doesn't need to know what each individual option does.

This option would probably make sense to expose in the spack package, rather than having a variant for each individual CMake option.