rename module Types to Codex_types

[S41d]

I had a Duplicated implementations error when trying to use Codex as a library for Owi using OCaml 5.4. This PR renames the Types module to Codex_types to prevent the aforementioned error.

[mlemerre]

Hi @S41d , do you know where the error comes from? I thought that dune was packing modules. Otherwise, it means that we cannot have internal modules with the same name?

[redianthus]

The error was the following:

$ ...
File "_none_", line 1:
Error:  Duplicated implementations:
         Multiple definitions of module Types in files /home/xyz/.opam/5.4.0/lib/codex/types/types.cmxa,
         /home/xyz/.opam/5.4.0/lib/ocaml/compiler-libs/ocamlcommon.cmxa
File "_none_", line 1:
Error:  Duplicated implementations:
         Multiple definitions of module Types in files /home/xyz/.opam/5.4.0/lib/codex/types/types.cma,
         /home/xyz/.opam/5.4.0/lib/ocaml/compiler-libs/ocamlcommon.cma
File "_none_", line 1:
Error:  Duplicated implementations:
         Multiple definitions of module Types in files /home/xyz/.opam/5.4.0/lib/ocaml/compiler-libs/ocamlcommon.cma,
         /home/xyz/.opam/5.4.0/lib/codex/types/types.cma

It does not come from Owi, but I think that trying to have both Codex + Owi makes the conflict appear because of stuff brought transitively by Owi (I suspect something related to dune-site + -linkall...)