Ideas for ocaml-team

[pukkamustard]

Hello Guix,

I think it's time to start an `ocaml-team` (or `ocaml-updates`) branch
to collect some bigger updates and changes to the OCaml packages in
Guix.

Some things that I can think of:

* Update OCaml from 4.14.0 to 4.14.1

* Update OPAM from 2.1.3 to 2.1.5
  - Requires a major update of ocaml-dose3 from 5.0.1 to 7.0.0

* Update Dune from 3.6.1 to 3.8.1

* Update Jane Street packages from 0.15.0 to 0.16.0

* Remove most ocaml4.07-* and ocaml4.09 packages
  - We only want to keep the compiler around for bootstrapping purposes.
  - Update unison 2.51.2 to 2.53.3: This makes it buildable with OCaml
    4.14 or even 5.0.  (see
    https://lists.gnu.org/archive/html/guix-devel/2023-02/msg00253.html).

* Split packages from (gnu packages ocaml) into multiple modules. Maybe
  in following modules:

  - (gnu packages ocaml): For the compiler and core dev packages (opam,
    dune, merlin)
  - (gnu packages ocaml-boot): For the 4.07 and 4.09 compilers
  - (gnu packages ocaml-xyz): Everything else

Thoughts? Any other things? How do we get started with such a branch? 

Cheers,
pukkamustard