## Summary
Adds type inference for list/dict/set comprehensions, including
bidirectional inference:
```py
reveal_type({k: v for k, v in [("a", 1), ("b", 2)]}) # dict[Unknown | str, Unknown | int]
squares: list[int | None] = [x for x in range(10)]
reveal_type(squares) # list[int | None]
```
## Ecosystem impact
I did spot check the changes and most of them seem like known
limitations or true positives. Without proper bidirectional inference,
we saw a lot of false positives.
## Test Plan
New Markdown tests
