DAL/Node: validate GS messages (version 1)

Context

Fixes #5558 (closed)

Validate GS full messages received via P2P using crypto.

Limitations of this first version

The current solution not satisfactory, as it adds a reference in the Gossipsub interconnection lib. A better solution would use a functor or a first class module, but this will require some refactoring. This will be done once the current MRs are merged?

During the refactoring, take into account the fact that we also want to make get_topic more complex (access to the context/L1, ...) to simplify topic & message_id types (and save bandwidth).

This issue will be addressed in #5674 (closed)

Manually testing the MR

dune exec -- tezt/tests/main.exe --file dal.ml --title "Alpha: Testing DAL node (GS invalid messages exchange)"

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR