[ty] Ignore type context when inferring `assert_never` arguments (#30389)
We internally declare the parameter type of the `assert_never` value to
be `Any`. However, this declared type should be ignored when inferring
the value expression, as it can sometimes prevent a nested generic call
from inferring `Never`, incorrectly silencing the assertion:
```py
from typing import Iterator, Never, assert_never
def _(items: Iterator[Never]):
assert_never(next(items)) # main: error[type-assertion-failure], now: ok
def result[T = Never]() -> T:
raise NotImplementedError
assert_never(result()) # main: error[type-assertion-failure], now: ok
```
Reported in
https://github.com/astral-sh/ty/issues/4988#issuecomment-6779572903.
ruff
b140af2f - [ty] Ignore type context when inferring `assert_never` arguments (#30389)
