also install stdlib and modularize build

.gitlab-ci.yml

Makefile

_CoqProject

case_studies/dune-project

case_studies/tests/src/lib.rs

case_studies/tests/src/option.rs

coq-caesium-config-no-align.opam

dune

flake.nix

rr_frontend/translation/src/lib.rs

...rontend/translation/src/spec_parsers/crate_attr_parser.rs

scripts/install-stdlib.sh

scripts/install-typesystem.sh

stdlib/Makefile

stdlib/alloc/src/lib.rs

stdlib/dune

stdlib/dune-project

stdlib/option/src/lib.rs

stdlib/refinedrust-stdlib.opam

stdlib/result/src/lib.rs