Fix restore proto activation

This MR is manifolds:

• improve protocol table consistency checks when starting the node,
• (lots of) refactoring,
• add a test to check that the protocols restoration is done as expected,
• fix and optimise the way the protocols table was restored.

Manually testing the MR

• dune exec ./src/lib_store/unix/test/test.exe --no-buffer -f -- test "consistency",
• Take the data directory of a node, break it (by removing the store/chain_xxx/protocols_table or another file), run your node and observe the behaviour.

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