One-way platform support for the KinematicCharacterController

### 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.

```rust
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."_