Fix push_input events not going through after first pressed mouse event

[Jummit]

Subviewports didn't update their parent's local_input_handled correctly.

The patch is basically the inverse of set_input_as_handled.

There is a small chance that this change is not the way to fix the issue, but it didn't create any problems in my case.

Fixes #76439.

Off-topic: Wow, that's some fast CI! Thanks Akien!

[Sauermann]

This PR was discussed in a recent Input-PR review meeting together with #77926.
We ended up with asking Reduz for his opinion.

[Sauermann]

This PR should be considered for 4.2 as a non-compatibility breaking alternative to #77926.

[AThousandShips]

Simplification suggestion

[Sauermann]

I have verified the problem of the linked issue and verified, that the MRP accurately represents the problem.
The MRP is still a problem in current master and this PR (rebased on [b9a3bd2]) solves the problem.

The code is in alignment with preexisting code

godot/scene/main/viewport.cpp

Lines 3657 to 3673 in d76c1d0

	if (!handle_input_locally) {
	ERR_FAIL_COND(!is_inside_tree());
	Viewport *vp = this;
	while (true) {
	if (Object::cast_to<Window>(vp)) {
	break;
	}
	if (!vp->get_parent()) {
	break;
	}
	vp = vp->get_parent()->get_viewport();
	}
	if (vp != this) {
	vp->set_input_as_handled();
	return;
	}
	}

and it is looking good to me.

While I believe that #77926 (removal of handle_input_locally) is a better solution in the long term, I consider it unlikely that it will get reviews in the near future, so at the moment the best approach to fix the linked issue is this PR.

[YuriSizov]

Thanks!