Monitoring: trace history, trace search, and x:Trace over the stored traces (MON-10 to MON-17, MON-32)

A lossy collector subscriber keeps each inbound SMTP session that reached
MAIL FROM and each delivery attempt, info level and above and never raw
I/O, at most 1,000 events with strings cut at 4 KiB, and writes it when
the span closes as an x:Trace under the telemetry key class, scheduling
its indexing. The index task builds a document of event types, queue ids
and keywords when indexTelemetry is on. x:Trace/get derives timestamp,
from, to and size; /query filters by opening event, text, queueId and
time; /set destroys only. The data purge honours holdTracesFor. The shared
tracing and webhook suites run.

crates/common/src/telemetry/mod.rs

@@ -102,6 +102,10 @@ impl TelemetrySubscriberType {
             TelemetrySubscriberType::LogTracer(settings) => spawn_log_tracer(builder, settings),
             TelemetrySubscriberType::Webhook(settings) => spawn_webhook_tracer(builder, settings),
             TelemetrySubscriberType::OtelTracer(settings) => spawn_otel_tracer(builder, settings),
+            // inbuxa: MON-10: trace history
+            TelemetrySubscriberType::StoreTracer(settings) => {
+                tracers::store::spawn_store_tracer(builder, settings.tracing, settings.data)
+            }
             #[cfg(unix)]
             TelemetrySubscriberType::JournalTracer(subscriber) => {
                 tracers::journald::spawn_journald_tracer(builder, subscriber)