Remove cmake-format check and support

Remove cmake-format check and support

Motivation:

1. It’s unsatisfying to have to remember to run “make format” after
   editing CMake files. (Clang-Format has more editor integrations, and
   most importantly there are integrations for my editor of choice.)
2. The output of cmake-format seems to be a bit unstable between
   versions.
3. I don’t like some of cmake-format’s formatting choices. This could be
   potentially be improved, though.

Let’s remove the support for now and maybe revisit later.