Tezt cloud DAL test snapshots support

This MR introduces the --snapshot option to use locally stored snasphot file, avoiding to download it from a provider at each run.

Manually testing the MR

Make use of --snapshot <path> and look for

[14:56:16.695] [TOP] Using locally stored snapshot file: ./recent_ghostnet_snapshot.rolling
[14:56:16.695] [file#6] file -L ./recent_ghostnet_snapshot.rolling
[14:56:16.697] [file#6] ./recent_ghostnet_snapshot.rolling: tar archive
[…]
[14:56:17.612] [TOP] Importing the snapshot for producer-node-1
[14:56:17.612] [producer-node-1] /tmp/tezt-runners/./octez-node snapshot import --data-dir /tmp/build_ce3861_dune/tezt-49487/1/producer-node-1 --no-check ./recent_ghostnet_snapshot.rolling

For example, run dune exec tezt/tests/cloud/main.exe -- DAL --producers 2 --producer-slot-indices 9,10 --log-file ghostnet-producers-05-27.log --network ghostnet --tezt-cloud ghostnet-8-producers --dockerfile-alias dal --fundraiser <private_key> --keep-temp -v --localhost --snapshot ./recent_ghostnet_snapshot.rolling

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