False negatives of `py/flask-debug`

`py/flask-debug` misses some common ways to enable debug mode in Flask.

For example:
```python
app = Flask(__name__)
app.config['DEBUG'] = True # Enables debug mode
app.run()

---
class Settings:
DEBUG = True

settings = Settings()
app.run(debug=settings.DEBUG)
```

Start by locating the py/flask-debug query and reproducing the two examples in the issue. Compare the query's behavior with both configuration-based and argument-based debug activation; done means these common Flask patterns are detected without regressing existing cases.

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