coqPackages.metacoq: update for coq 8.17 and 8.18 (#273541)
Also update default.nix to match the default.nix in
MetaCoq/metacoq:.nix/coq-overlays/metacoq/default.nix
Because some files have changed names, some version-dependent
building is required to keep building older versions.
And Metacoq's default.nix had older version checksums.
We use the more recent versions from nixpkgs for coq 8.14-8.16
Co-authored-by: Lars Rasmusson <Lars.Rasmusson@rise>
authored by larsr Lars Rasmusson and committed by GitHub 5d43a876 23959be5