Fix Snap 2d Transforms To Pixel gaps

[jtakakura]

Fixes #56793

[akien-mga]

I haven't looked at details but I believe this might solve the issue in some cases, and worsen the situation in other cases. @lawnjelly did a deep dive into this stuff for Godot 3 and this was a huge can of worms.

[jtakakura]

@lawnjelly Please tell me how to test this issue if you know.
This issue is a significant impact on pixel game developers.

[lawnjelly]

Here's a list of some reading for you:
#57221 (comment)

We did try different round modes if I remember right (was a couple years ago).

[jtakakura]

@lawnjelly Thank you for your reply
I found the reason you revert the similar modifications in #46615 (comment)
I understood this problem is very complicated

[lawnjelly]

BTW this is not trying to discourage work on this area, it is clearly quite important to a lot of users, but tricky to get right (I just gave up with lack of patience in the end 😃 , might have to revisit it now we are doing 2D interpolation ).

Probably will need some proper thought and a proposal to discuss how to proceed to properly solve this area.

[akien-mga]

Also, I think if we can't find a one-size-fits-all solution, but can design different solutions that work in different use cases, we could implement those multiple solutions and make them selectable (and provide guidance on which mode to use for which use case).

[jtakakura]

Sorry for the late reply.
I looked at ways to solve this issue but I couldn't come up with a one-size-fits-all solution.
Then I would like to consider how to solve referring to the following PR.
Thanks.

#46615