Add tool to check the safety of the network

Context

Closes #6300 (closed).

Manually testing the MR

dune build devtools/testnet_experiment_tools

./_build/default/devtools/testnet_experiment_tools/safety_checker.exe check \
     --data-dir <data_dir> \
     --protocol <protocol> \
     --min-unsafe-round <min_unsafe_round> \
     --max-maybe-unsafe-ratio <max_maybe_unsafe_ratio> \
     --min-maybe-unsafe-round <min_maybe_unsafe_round>

<data-dir> - directory where the node context is stored

<protocol> - the protocol used for the network

<min-unsafe-round> - all blocks are required to have round less than it

<max-maybe-unsafe-ratio> - no more than this percentage of blocks should have at least [min-maybe-unsafe-round] round

<min-maybe-unsafe-round> - limit the number of blocks with at least this round

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