Tezt: Agnostic_accuser: Add migration scenarios

What

Parent MR: !17905 (merged)

This MR achieves the removal of the use of the protocol dependent accuser binaries in tezt, replacing them with the newly added agnostic accuser

Why

To test that during migrations, the agnostic accuser behaves correctly.

How

Manually testing the MR

CI green + in particular

dune exec tezt/tests/main.exe -- --file double_consensus.ml --verbose

All tests should pass.

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