List all concrete playback tests in the test tab

[celinval]

Requested feature: List the concrete playback in the tests tab after all harnesses. This is how it looks today:

I would suggest that we do something like:

\/ Kani Proofs
  \/ main.rs
    ✅ harness_true
    ....
\/ Concrete Playback
  \/ main.rs
    ❌ kani_concrete_playback_check_estimate_size_14615086421508420155

Use case:
Link to relevant documentation (Rust reference, Nomicon, RFC):

Test case:

<code>