WASM: Allow each WASM PVM revision to have its set of host functions

Context

• Previous MR: !7910 (merged)

This is again a pure refactoring, with no semantics change, and the last piece before being able to add new host functions to the WASM PVM in a non-breaking way.

The chosen approach is expected to preserve performances.

Manually testing the MR

CI shall prevail.

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