Plug DAL refutation functions in SCORU refutation game

Context

fixes #3925 (closed).

The second part of the extension of Scoru refutation game with DAL refutation (WIP: needs cleaning & more tests):

For a more detaild spec & explanation, see https://hackmd.io/k3N8m3zgRQSjT7-JpquTxw

What has been done in this MR, for short:

• Extend sc_rollup_PVM_sem with a new kind of reveal (input & input_request)
• Plug Dal refutation functions in sc_rollup_proof_repr
• Extend Proto's refutation game to snapshot and provide DAL skip list when verifying a proof
• Extend PVM Arith to be able to request & accept pages inputs
• Extend PVM Arith's syntax with "dal::<slot_id>:<page_id>". The intended semantics is to request the corresponding page
• Extend the rollup node's interpreter to handle Dal pages evaluation.
• Add a tezt test where the Arith PVM correctly interprets the content of a confirmed and unconfirmed slot's pages.

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
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• 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).
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