report error when ambiguous `FunctionType` as `Enum` value

### Describe the Bug

```py
from enum import Enum

def f() -> object:
return lambda: 1

class E(Enum):
a = f() # expect error: `object` can potentially be `FunctionType`, wrap this value with `enum.member` to enforce expected runtime behaviour

E.a.name # fails at runtime
```

`FunctionType` becomes a non-member, but currently pyrefly assumes a super type of `FunctionType` is a member, use `enum.member` to override this and make it a member

in this case i would expect `E.a` to become either `Unknown` or a type of `member | non-member`, either way i would expect an error message to be shown on the declaration of `E.a`

### Sandbox Link

_No response_

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

_No response_