Monitoring: alerts over metrics, by event and by email (MON-25 to MON-30)

Every minute the node that calculates metrics evaluates each enabled
x:Alert, read from the registry, with metric('name') or the underscore
name. An alert fires when its condition turns true: it emits
telemetry.alert-event with the rendered message, and queues one email per
recipient through the outbound queue, placeholders filled and
Auto-Submitted set. An alert naming an unknown metric is refused on save.
The shared alerts suite runs; every telemetry suite is un-gated.

tests/src/telemetry/mod.rs

@@ -4,7 +4,6 @@
  * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
  */
 
-#[cfg(feature = "pending-rebuild")] // inbuxa: pending-rebuild, see docs/spec/features/
 pub mod alerts;
 pub mod metrics;
 pub mod tracing;
@@ -56,7 +55,6 @@ pub async fn telemetry_tests() {
         .await;
     test.insert_account(admin);
 
-    #[cfg(feature = "pending-rebuild")]
     alerts::test(&test).await;
     metrics::test(&test).await;
     tracing::test(&test).await;