logical/framework: add a field data type for parsing integer arrays (#4064)

* logical/framework: add a field data type for parsing integer arrays

* Fix comment

* Add zero value

logical/framework/backend.go

@@ -593,6 +593,8 @@ func (t FieldType) Zero() interface{} {
 		return []interface{}{}
 	case TypeStringSlice, TypeCommaStringSlice:
 		return []string{}
+	case TypeCommaIntSlice:
+		return []int{}
 	default:
 		panic("unknown type: " + t.String())
 	}