One-way platform support for the KinematicCharacterController

[DevinLeamy]

Overview

One-way platforms are not supported for the KinematicCharacterController because it doesn't depend on the "solver" to resolve collisions.

E.g. following the conventional approach and using PhysicsHooks will not work.

impl BevyPhysicsHooks for OneWayPlatformHook {
    fn modify_solver_contacts(&self, context: ContactModificationContextView) {
        context.raw.update_as_oneway_platform(...);
    }
}

For the KinematicCharacterController to support one-way platforms, "it would have to run some checks internally to ignore collisions with normals outside of a particular angle wrt. the up direction."