use digestif hashes

[samoht]

Use Digestif.S instead of custom hash signature

The patch is too invasive to my taste, but I had to flatten a lot of the modules hiearchies to make everyting compile...

[dinosaure]

Ok, a big PR about functor hell.

• One other question is about Inflate and Deflate, it's really needed to keep them in interfaces?
• If we need to provide Map.S and Set.S in digestif
• Digestif.S.eq or Digestif.S.equal?

And then, an ocamlformat pass is really needed at the end.

[dinosaure]

Why X... ?

[dinosaure]

We need to choose between eq and equal but have both is not a good idea. I think equal should be the best and I can change API of Digestif.S to provide equal instead eq but we need to choose one - then if we choose equal, we need to update this PR to replace any H.eq to H.equal.

[samoht]

yes I think Digestif.S should provide equal instead of eq.

[samoht]

Rebased and fixed to take the comments into account.

[samoht]

Odd constraints on windows:

The following dependencies couldn't be met:
  - git-mirage -> git -> digestif >= 0.7.0 -> eqaf -> core_bench -> comparelib >= 109.27.00 -> type_conv < 112.02.00
  - git-mirage -> git -> digestif >= 0.7.0 -> eqaf -> core_bench -> core < v0.10
  - git-mirage -> git -> digestif >= 0.7.0 -> eqaf -> core_bench -> fieldslib = 109.20.00
  - git-mirage -> git -> digestif >= 0.7.0 -> eqaf -> core_bench -> sexplib < 113.25.00
  - git-mirage -> git -> digestif >= 0.7.0 -> eqaf -> core_bench -> textutils >= 112.17.00 -> sexplib < 113.25.00
  - git-mirage -> git -> digestif >= 0.7.0 -> eqaf -> core_bench -> textutils >= 112.17.00 -> core < v0.10

[samoht]

The windows issues should be fixed by ocaml/opam-repository#12575