Add an overload for int, str and bool

[GameRoMan]

Adds overlaods for __new__ method in int, str and bool classes, when no value is provided as an argument

[JelleZijlstra]

This is incorrect for int and str because on subclasses, this returns an instance of the subclass, not of str or int itself.

[AlexWaygood]

this doesn't stop the overload from applying to subclasses, because type[bool] is a subtype of type[int], for example (bool is a subclass of int)

[JelleZijlstra]

Yeah I don't think the current type system has a way to fix the issue I brought up.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

colour (https://github.com/colour-science/colour)
+ colour/notation/hexadecimal.py:135: note:     def __new__(cls) -> int

discord.py (https://github.com/Rapptz/discord.py)
+ discord/app_commands/models.py:223: note:     def __new__(cls) -> int

ibis (https://github.com/ibis-project/ibis)
+ ibis/common/temporal.py:203: note:     def __new__(cls) -> int

[JelleZijlstra]

We could do this for bool (which can't have subclasses) but I don't think we can make it work for int or str, and I don't see much point in the change anyway.

For bool we should remove the = ... for the second overload, so the overloads don't overlap. We also don't need the type[bool] annotation.

I'm somewhat hesitant to accept the change for bool too, since changes to core stubs can sometimes have unintended consequences, and I don't see much benefit here. The mypy-primer output is promising, though.

[AlexWaygood]

Going to close for now. I'd personally be inclined to accept a PR that just made the change to bool.__new__ (we already hardcode that knowledge into ty), but IIRC it might break a lot of mypy tests, as mypy often assumes that bool() is going to return a bool in its test suite. So it would be good to check that it wouldn't be hugely disruptive to mypy if it was a bool-only PR (I agree with @JelleZijlstra that the benefits are fairly slim, so it's not worth it if it would cause a lot of hassle for mypy IMO)