Use ocaml setup, more opam

.github/workflows/check_encoding.yml

.github/workflows/proof_tools.yml

.github/workflows/pvs_prelude.yml

proofs/appaxiom/appaxiom.opam

proofs/appaxiom/dune-project

proofs/chainprops/chainprops.opam

proofs/chainprops/dune-project

tools/personoj.opam

tools/setup-pvs.sh