For an abstract class in the CodeQL source code, how can I quickly find all the classes that extend this abstract class from the CodeQL library?

Dear CodeQL Team,

I hope this message finds you well. I have a question regarding efficiently identifying subclasses of an abstract class in the CodeQL source code. Specifically:

For an abstract class in the CodeQL source code, is there a way to quickly find all the classes that extend this abstract class within the CodeQL library?

For example, consider the following class:

```ql
module PathInjection {
abstract class Sanitizer extends DataFlow::Node { }
}
```
Its subclasses are distributed across multiple files. Using search tools, I would have to search for patterns like `extends .*Sanitizer` and `extends .*PathInjection::Sanitizer`, etc., which is very cumbersome.

Thank you in advance for your time and assistance!

Start by reviewing the CodeQL library source and documentation around the abstract Sanitizer class in the PathInjection module. Determine whether the library or its tooling provides a way to enumerate subclasses across files, and document the quickest supported approach; no specific file or test is named in the issue.

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