Modules generated for sites use an implicit transitive dep

[rizo]

Expected Behavior

Compiling modules created with generate_sites_module when implicit_transitive_deps is set to false should work.

Actual Behavior

It doesn't, failing with:

     ~section:Dune_section.Share
              ^^^^^^^^^^^^^^^^^^
Error: Unbound module Dune_section

From what I understand, the dune-site lib implicitly depends on dune-private-libs.dune-section.

As a workaround the library that uses sites can directly depend on dune-private-libs.dune-section.

Specifications

• Version of dune (output of dune --version): 3.12.1
• Version of ocaml (output of ocamlc --version): 5.1.0
• Operating system (distribution and version): macOS 14

[nojb]

While working on #9333, @MA0010 remarked that the issue here is that the dune-site library should "re-export" dune-section library, since the code generated by Dune for sites mention Dune_section which is a module of dune-section. @MA0010 will submit a PR with the fix.