message: update_agent: log relevant transaction events
  This augments logging at the default level in order to show when
  (possibly long-running) rpm-ostree transactions start.
diff: @@ -95,11 +95,11 @@ impl UpdateAgent {
  let initialization = self.nop().map(|_r, actor, _ctx| {
  if actor.enabled {
  - actor.state.initialized();
  log::info!("initialization complete, auto-updates logic enabled");
  + actor.state.initialized();
  } else {
  - actor.state.end();
  log::warn!("initialization complete, auto-updates logic disabled by configuration");
  + actor.state.end();
  }
  });
  @@ -114,8 +114,8 @@ impl UpdateAgent {
  let state_change =
  actix::fut::wrap_future::<_, Self>(report_steady).map(|is_steady, actor, _ctx| {
  if is_steady {
  - actor.state.steady();
  log::debug!("reached steady state, periodically polling for updates");
  + actor.state.steady();
  }
  });
  @@ -190,12 +190,16 @@ impl UpdateAgent {
  return Box::new(actix::fut::err(()));
  }
  + log::info!(
  + "new release '{}' selected, proceeding to stage it",
  + release.version
  + );
  let msg = rpm_ostree::StageDeployment { release };
  let upgrade = self
  .rpm_ostree_actor
  .send(msg)
  .flatten()
  - .map_err(|e| log::error!("failed to stage update: {}", e))
  + .map_err(|e| log::error!("failed to stage deployment: {}", e))
  .into_actor(self);
  Box::new(upgrade)
  @@ -211,12 +215,16 @@ impl UpdateAgent {
  return Box::new(actix::fut::err(()));
  }
  + log::info!(
  + "staged deployment '{}' available, proceeding to finalize it",
  + release.version
  + );
  let msg = rpm_ostree::FinalizeDeployment { release };
  let upgrade = self
  .rpm_ostree_actor
  .send(msg)
  .flatten()
  - .map_err(|e| log::error!("failed to finalize update: {}", e))
  + .map_err(|e| log::error!("failed to finalize deployment: {}", e))
  .into_actor(self);
  Box::new(upgrade)
  