Testnet stresstest tools - Generate network configuration

Context

Follows !9712 (merged) and !9742 (merged). This MR implements the script needed to generate the node configuration for a new testnet, with an empty set of bootstrap peers.

Manually testing the MR

dune build devtools/testnet_experiment_tools 
BAKERS=10 OUTPUT_DIR=<output_dir> dune exec devtools/testnet_experiment_tools/testnet_experiment_tools.exe -- generate_baker_accounts
OUTPUT_DIR=<output_dir> dune exec devtools/testnet_experiment_tools/testnet_experiment_tools.exe -- generate_network_configuration

The result should look like this:

$ cat <output_dir>/config.json

{ "data-dir": "gen_keys_dir/",
  "network":
    { "genesis":
        { "timestamp": "2023-09-20T12:19:35Z",
          "block": "BLockGenesisGenesisGenesisGenesisGenesis4a56dftNz2h",
          "protocol": "Ps9mPmXaRzmzk35gbAYNCAw6UXdE2qoABTHbN2oEEc1qM7CwT9P" },
      "genesis_parameters":
        { "values":
            { "genesis_pubkey":
                "edpkvMwxctNixMJ1wdegKKwb751a4ZmEdLMjGwP5VWuDWgeVet87fu" } },
      "chain_name": "TEZOS_EXPERIMENT_NET",
      "sandboxed_chain_name": "TEZOS_EXPERIMENT_NET_SANDBOXED" } }

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