Added basic regression test for the CV based on metatensor that Ali a… #24

Job	Run time
codecheck / codecheck	2m 0s
docker / docker (fedora39)	8m 18s
conda / conda (ubuntu-20.04)	10m 50s
docker / docker (rocky8)	9m 35s
linux / linux (-doc-mpi-)	1m 36s
conda / conda (macos-12)	30m 13s
linux / linux (-mpi-)	24s
mac / macports (macos-12)	21m 12s
conda / conda (macos-14)	8m 22s
linux / linux (-coverage-mpi-)	1m 21s
mac / macports (macos-14)	10m 57s
mac / macsimple (macos-12)	10m 50s
linux / linux (-debug-)	1m 35s
mac / macports (+allmodules, macos-12)	12m 8s
mac / macsimple (macos-14)	5m 12s
linux / linux (-debug-mpi-)	1m 25s
linux / linux (-intel-)	29s
linux / linux (-pycv-mpi-)	26s
	2h 16m 53s

Provide feedback