Tezt_cloud: Add accusers option for layer1 scenario

What

Parent MR : !17873 (closed)

Add --accusers option to decide which bakers from the Layer1 scenario to run with --with-accuser argument.

Why

How

Manually testing the MR

TEZT_CLOUD=debian dune exec tezt/tests/cloud/main.exe -- LAYER1 -v --log-file /tmp/log \
   --localhost \
   --stake 2,1,1 \
   --accusers 0,2 \
   --migration-offset 20 \
   --network ghostnet \
   --faketime "-$(($(date --utc +%s) - $(date --date $(./octez-node snapshot info --json ./ghostnet.snapshot | jq -r .snapshot_header.timestamp) +%s)))" \
   --prometheus \
   --grafana \
   --website \
   --snapshot ./ghostnet.snapshot \
   --monitoring

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