Do some include shuffling for `**.h` files within lib, programs, tests, and zlibWrapper.
`lib/legacy` and `lib/deprecated` are untouched.
`#include`s within `extern "C"` blocks in .cpp files are untouched.
todo: shuffling for `xxhash.h`
CMake warns on the current minimum requirement (3.5). Update to 3.10.
This means support is still available for the default on Ubuntu 18.04, which
exited LTS standard in April of 2023.
[draft]