Add QMS for online migration (#1870)

* Add QMS for online migration

* Fix lint

---------

Co-authored-by: kbhat1 <kartikbhatri@gmail.com>

app/seidb.go

@@ -34,6 +34,8 @@ const (
 
 	// Other configs
 	FlagSnapshotInterval = "state-sync.snapshot-interval"
+	FlagMigrateIAVL      = "migrate-iavl"
+	FlagMigrateHeight    = "migrate-height"
 )
 
 func SetupSeiDB(
@@ -58,8 +60,15 @@ func SetupSeiDB(
 	// cms must be overridden before the other options, because they may use the cms,
 	// make sure the cms aren't be overridden by the other options later on.
 	cms := rootmulti.NewStore(homePath, logger, scConfig, ssConfig)
+	migrationEnabled := cast.ToBool(appOpts.Get(FlagMigrateIAVL))
+	migrationHeight := cast.ToInt64(appOpts.Get(FlagMigrateHeight))
 	baseAppOptions = append([]func(*baseapp.BaseApp){
 		func(baseApp *baseapp.BaseApp) {
+			if migrationEnabled {
+				originalCMS := baseApp.CommitMultiStore()
+				baseApp.SetQueryMultiStore(originalCMS)
+				baseApp.SetMigrationHeight(migrationHeight)
+			}
 			baseApp.SetCMS(cms)
 		},
 	}, baseAppOptions...)