Add `Variable::chunking` #347

Job	Run time
test apt (stable)	44s
static builds (ubuntu-latest, stable)	1m 21s
test apt (beta)	40s
static builds (windows-latest, stable-msvc)	6m 21s
test apt (nightly)	44s
static builds (windows-latest, stable-gnu)	5m 6s
static builds (macos-12, stable)	3m 14s
static builds (macos-latest, stable)	1m 41s
mpi-runner	1m 25s
conda (ubuntu, conda-forge, stable)	57s
Address sanitizer	1m 23s
conda (windows, conda-forge, stable)	2m 19s
rustfmt	1m 5s
conda (macos, conda-forge, stable)	1m 3s
	28m 3s

Provide feedback