feat: migrator support table comment

migrator.go

@@ -76,6 +76,7 @@ type Migrator interface {
 	HasTable(dst interface{}) bool
 	RenameTable(oldName, newName interface{}) error
 	GetTables() (tableList []string, err error)
+	GetTableComment(tableName string) (comment string, err error)
 
 	// Columns
 	AddColumn(dst interface{}, field string) error

migrator/migrator.go

@@ -947,3 +947,8 @@ func (m Migrator) GetIndexes(dst interface{}) ([]gorm.Index, error) {
 func (m Migrator) GetTypeAliases(databaseTypeName string) []string {
 	return nil
 }
+
+// GetTableComment return table comment
+func (m Migrator) GetTableComment(tableName string) (string, error) {
+	return "", errors.New("not support")
+}