[`pylint`] Also report when the object isn't a literal (`PLE1310`) (#15985)
## Summary
Follow-up to #15984.
Previously, `PLE1310` would only report when the object is a literal:
```python
'a'.strip('//') # error
foo = ''
foo.strip('//') # no error
```
After this change, objects whose type can be inferred to be either `str`
or `bytes` will also be reported in preview.
## Test Plan
`cargo nextest run` and `cargo insta test`.