Add Jetstream error info somewhere outside Results page

[mikewilli]

An issue with the new Errors UI work is that if Jetstream fails to produce any results at all, the Results page may not even be visible to display any errors. We should consider displaying errors and/or analysis start time info to the Summary page and/or the Sidebar where it currently says analysis not ready yet (see screenshot below).

Perhaps if there is an experiment error, we could instead show "Analysis performed at failed with error <ErrorName>" (or similar).

┆Issue is synchronized with this Jira Task

[mikewilli]

Example experiment with analysis error https://experimenter.services.mozilla.com/nimbus/task-continuity-sync-after-tab-change-rollout-60