chore(db): add ability to wait for programmatically started database maintenance, query last maintenance time (#10565)

Also adds a method to query the last database maintenance time.

Signed-off-by: Tommy van der Vorst <tommy@pixelspark.nl>
Co-authored-by: Jakob Borg <jakob@kastelo.net>

internal/db/interface.go

@@ -19,7 +19,12 @@ type DBService interface {
 	suture.Service
 
 	// Starts maintenance asynchronously, if not already running
-	StartMaintenance()
+	// Returns a channel that will receive the result when the requested maintenance finishes
+	StartMaintenance() <-chan error
+
+	// Returns the last time database maintenance completed
+	// This will return time zero when database maintenance has never completed successfully.
+	LastMaintenanceTime() time.Time
 }
 
 type DB interface {