`re.Pattern` shouldn't be allowed in `helpful-string`

```py
import re

re_compile = re.compile("a")
print(re_compile) # re.compile('a')
print(type(re_compile)) #
```

No source file or test is named. Start by reproducing the shown re.compile example with basedmypy and locate the implementation or tests for the `helpful-string` behavior; done means `re.Pattern` is rejected there while the expected existing cases remain supported.

Written by the indexing model from the issue text.