DAL: Get aggregated attestations

What

Extend the DAL plugin to deal with aggregated attestations.

Why

Since some attestations with DAL are now aggregated, it is necessary to consider them in the DAL node.

How

By extending the get_attestations function in S DAL plugin and by adding a tb_slot argument to the inject_entrapment_evidence function to be able to access the denunced attestation in an aggregation.

Manually testing the MR

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