DAC: Introduce experimental (but binding) `V0` API

Context

For more details see #5581 (closed). For how it fits in the big picture see #5437 (closed). This MR introduces experimental V0 API, that will be used by the 1M/tps demo and is as such binding from now on. Builds on the idea of !8554 (closed).

Closes #5581 (closed)

See !8750 (merged) for the follow-up.

Manually testing the MR

CLI should pass: dune exec tezt/tests/main.exe -- --file dac.ml

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