In #303 `#[test_attr]` was introduced. Refactor to remove parse and error logic from render stage. What is missed now: - [x] lot of parsing test - [x] e2e test for `test_attr` - [x] ~e2e~ test invalid attribute in #[test_attr(...)]` - [x] e2e test that use `smol` - [x] changelog - [x] review docs
