multi: pass in a MigrationConfig to all optional migrations

Define a MigrationConfig interface that should be used to pass the
config of an optional migration function. An implementation of this
interface is added for migration30 (the only current optional
migration).

channeldb/migration30/migration.go

@@ -23,10 +23,17 @@ import (
 // indexes.
 const recordsPerTx = 20_000
 
+// MigrateRevLogConfig is an interface that defines the config that should be
+// passed to the MigrateRevocationLog function.
+type MigrateRevLogConfig interface{}
+
+// MigrateRevLogConfigImpl implements the MigrationRevLogConfig interface.
+type MigrateRevLogConfigImpl struct{}
+
 // MigrateRevocationLog migrates the old revocation logs into the newer format
 // and deletes them once finished, with the deletion only happens once ALL the
 // old logs have been migrates.
-func MigrateRevocationLog(db kvdb.Backend) error {
+func MigrateRevocationLog(db kvdb.Backend, _ MigrateRevLogConfig) error {
 	log.Infof("Migrating revocation logs, might take a while...")
 
 	var (

channeldb/migration30/migration_test.go

@@ -103,11 +103,15 @@ func TestMigrateRevocationLog(t *testing.T) {
 				return nil
 			}
 
+			cfg := &MigrateRevLogConfigImpl{}
+
 			migtest.ApplyMigrationWithDB(
 				t,
 				beforeMigration,
 				afterMigration,
-				MigrateRevocationLog,
+				func(db kvdb.Backend) error {
+					return MigrateRevocationLog(db, cfg)
+				},
 				false,
 			)
 		})
@@ -559,6 +563,8 @@ func BenchmarkMigration(b *testing.B) {
 		return setupTestLogs(db, c, oldLogs, nil)
 	}
 
+	cfg := &MigrateRevLogConfigImpl{}
+
 	// Run the migration test.
 	migtest.ApplyMigrationWithDB(
 		b,
@@ -568,7 +574,7 @@ func BenchmarkMigration(b *testing.B) {
 			b.StartTimer()
 			defer b.StopTimer()
 
-			return MigrateRevocationLog(db)
+			return MigrateRevocationLog(db, cfg)
 		},
 		false,
 	)