Plugins contribute TraceSinkFactory functions; the process-manager
capability invokes each factory with the runtime's
ServiceResolver$.ServiceResolver, collects the resulting
Trace$.Sinks, merges them via Trace$.mergeSinks, and
installs the merged sink as Trace$.TraceSink in the runtime layer
so every process writes to every contributed sink.
Trace sink contribution.
Plugins contribute TraceSinkFactory functions; the process-manager capability invokes each factory with the runtime's ServiceResolver$.ServiceResolver, collects the resulting Trace$.Sinks, merges them via Trace$.mergeSinks, and installs the merged sink as Trace$.TraceSink in the runtime layer so every process writes to every contributed sink.