SCORU: Make the PVMs compliant with the Rollup Management Protocol

Context

The inbox now contains messages from Sc_rollup.Inbox.Message but the PVMs were not updated to take this into account. This was not detected because no inbox proofs were exercising the consistency between the rollup node inbox and the official inbox.

This MR fixes this inconsistency and also introduces the possibility to check the values stored in the PVMs in tezt tests.

This MR does not introduce new tests to detect inconsistencies

Manually testing the MR

dune exec tezt/tests/main.exe -- --file sc_rollup.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