Check for `__bool__` for if/while conditions

[grievejia]

Describe the Bug

Minimal repro:

class NotBoolable:
    __bool__: int = 3

if NotBoolable():
    pass

Actual: no error Expected: NotBoolable() is not convertible to bool

Sandbox Link

https://pyrefly.org/sandbox/?code=MYGwhgzhAEByD2AXAQve4BGICmAuAUNEdAPokZohm7QCWAdotALzQDM++tAZnEqujBZsACgCUBYtAAOkCEA

(Only applicable for extension issues) IDE Information

No response

[ndmitchell]

@martindemello is working on this.

[martindemello]

fixed by 8ec4bca