Hook to run functions after invariant test run

### Describe the desired feature

Foundry allows defining a function `afterInvariant` that runs after invariant tests. It's briefly mentioned in the docs on [this page](https://getfoundry.sh/forge/advanced-testing/invariant-testing/).

We're [using ](https://github.com/EspressoSystems/espresso-network/blob/c66c977dbc5dc2f40156d40129b66725919c8c93/contracts/test/StakeTableV2.invariant.t.sol#L31) it to run print some stats, run some extra asserts that are slow to run and to withdraw all funds from a contract to ensure all users can withdraw what they own.

I couldn't find such functionality in echidna so currently I'm skipping it for [our echidna test](https://github.com/EspressoSystems/espresso-network/blob/29beb4e68ec59f342048454c9c8d0b5331d71b9f/contracts/test/StakeTableV2.echidna.sol#L33). Is it currently possible to do something along those lines? If not, is this a feature you could consider adding?

Start with the invariant-testing documentation and the linked StakeTableV2.invariant.t.sol and StakeTableV2.echidna.sol examples to understand the requested afterInvariant behavior. Then locate Echidna's invariant test execution path and determine where a post-run hook could be exposed. Done means documenting whether the behavior is possible or adding a tested hook that runs after invariant tests.

Written by the indexing model from the issue text.