feature: add plugin file date/hash to plugin load messages & logs for auditing

[leondz]

goal

output run summaries, including scores, garak versioning info, dates, a supplied asset ID, and analysis, as a record for asset audit trails

In all cases, we want to get the answer quickly, with minimum forensic work load.

suggestion

• at garak load,
  • log gh current hash if known
    • in garak.log
    • in report.jsonl
• at plugin load,
  • log file date as info (use same date as the cache uses)

Scenario 1:

We discover a few months post-hoc that one of our dev runs was really interesting, and we want to know if it was done using using stock or adjusted probes.

Scenario 2:

We find an old .post1-versioned log and want to know which version of a detector was used.

Scenario 3:

An external collaborator reports a bug and includes the last screenful (say 80 rows) of the log. We want to work out if they're using a proper version of garak or their own tweaked one.