The Harness's version in each Session trace #986

Parent

#700

What to build

Each session records the version its Harness reports, as a resource attribute of its Session trace, so that evals can split by Harness version. The version comes from the Harness's stream where it reports one, and otherwise from its version command, read once per Command for each Harness. #978 will reuse it in the pull request's Built-with line, and #977 will reuse it to record and fix each Arm's Harness versions.

Acceptance criteria

• Every Session trace's resource names its Harness's version, for all six Harnesses (the fakes report versions).
• A Harness that reports no version is recorded as unknown, and the session never fails over it.
• The version is read once per Command for each Harness, not once per event or session.