One way platforms don't have consistent collision on edge

[sicienss]

Godot version:
3.1

OS/device:
Windows 8, Toshiba Satellite

Issue description:
This is a rehash of closed issue #14724.

One-way StaticBody2Ds with rectangular CollisionShape2Ds do not consistently detect collision with a KinematicBody2D player when the player is on the edge of the platform.

Here is a video demonstrating the issue:

Even at low velocity, sometimes the player falls through the platform.

The player's movement is done by move_and_slide(), but the issue is also present when using move_and_slide_with_snap().

Steps to reproduce:

1. Create a basic platformer with a rectangular player and a rectangular one-way platform.
2. Position the player atop the one-way platform on an edge.
3. Jump repeatedly until the player falls through.
4. Adjust nearness to edge if you can't reproduce immediately.

Minimal reproduction project:
test_project.zip

[akien-mga]

Confirming that the issue is still reproducible with the attached project. PR #36280 aims at fixing it (and many others).

[capnm]

I can confirm, it's broken in v3.2.3.stable and #40645 #38471
#42574 (#42575) fixed the issue for me in the 3.2 branch.

[madmiraal]

No longer fixed by #42574 (#42575).

At high speed and when close to the edge, the collision normal returned is the normal of the side, not the top of the CollisionShape. One-way collisions treat collisions with the side as pass-through, hence the object falls through at high speed when close to the edge. Not visible with a normal shape for the same reason as #23140.

Related to #43014.