src: trace_event: secondary storage for metadata

Metadata trace-events should be held in secondary storage so that they
can be periodically reemitted. This change establishes the secondary
storage and ensures that events are reemitted on each flush.

PR-URL: https://github.com/nodejs/node/pull/20900


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>