More post-review changes, lots of tests for SubscribeActorEvents

Use BlockDelay as the window for receiving events on the SubscribeActorEvents
channel. We expect the user to have received the initial batch of historical
events (if any) in one block's time. For real-time events we expect them to
not fall behind by roughly one block's time.

node/modules/actorevent.go

@@ -10,6 +10,7 @@ import (
 	"github.com/filecoin-project/go-address"
 	"github.com/filecoin-project/go-state-types/abi"
 
+	"github.com/filecoin-project/lotus/build"
 	"github.com/filecoin-project/lotus/chain/events"
 	"github.com/filecoin-project/lotus/chain/events/filter"
 	"github.com/filecoin-project/lotus/chain/messagepool"
@@ -163,18 +164,16 @@ func EventFilterManager(cfg config.FevmConfig) func(helpers.MetricsCtx, repo.Loc
 
 func ActorEventHandler(enable bool, fevmCfg config.FevmConfig) func(helpers.MetricsCtx, repo.LockedRepo, fx.Lifecycle, *filter.EventFilterManager, *store.ChainStore, *stmgr.StateManager, EventHelperAPI, *messagepool.MessagePool, full.StateAPI, full.ChainAPI) (*full.ActorEventHandler, error) {
 	return func(mctx helpers.MetricsCtx, r repo.LockedRepo, lc fx.Lifecycle, fm *filter.EventFilterManager, cs *store.ChainStore, sm *stmgr.StateManager, evapi EventHelperAPI, mp *messagepool.MessagePool, stateapi full.StateAPI, chainapi full.ChainAPI) (*full.ActorEventHandler, error) {
-		ee := &full.ActorEventHandler{
-			MaxFilterHeightRange: abi.ChainEpoch(fevmCfg.Events.MaxFilterHeightRange),
-			Chain:                cs,
-		}
 
 		if !enable || fevmCfg.Events.DisableRealTimeFilterAPI {
-			// all Actor events functionality is disabled
-			return ee, nil
+			fm = nil
 		}
 
-		ee.EventFilterManager = fm
-
-		return ee, nil
+		return full.NewActorEventHandler(
+			cs,
+			fm,
+			time.Duration(build.BlockDelaySecs)*time.Second,
+			abi.ChainEpoch(fevmCfg.Events.MaxFilterHeightRange),
+		), nil
 	}
 }