support pytest fixture type infer

### Describe the Bug

since we now can go to definition of pytest fixture, how about add auto type annotation to parameter.

```py
@fixture
def x():
return 1
def test_x(x: Literal[1]):
...
```

the `: Literal[1]` is inferred.

### Sandbox Link

_No response_

### (Only applicable for extension issues) IDE Information

_No response_