Implement Sync to Physics property for KinematicBody3D (like in 2D)

[fabriceci]

This issue come from the main repository, I moved it here as suggested

Describe the problem or limitation you are having in your project:

Godot 3.1 added the "sync to physics" checkbox to fix the following issue: when a body is on a platform, he slowly slides over it when the platform change direction (because the motion is a frame ahead than the physics)

There is the same issue in 3D but this feature was not added yet on the KinematicBody3D