Dynamically adding/removing carousel slides with the `loop` property is glitchy

Describe the bug

When adding slides to a looping sl-carousel dynamically, the clone slides present challenges.

To Reproduce

Steps to reproduce the behavior:

1. Go to the sl-carousel docs page
2. Scroll to the add/remove example
3. Modify the dom in your browser to add the loop attribute to the sl-carousel
4. Try to use the example to add/remove slides.

Additional information

This could probably be solved by having the clone slides live outside the slot.

Pseudocode alert!

render() {
...
  if (loop) {
    <sl-carousel-clone></sl-carousel-clone>
  }
  <slot></slot>
  if (loop) {
    <sl-carousel-clone></sl-carousel-clone>
  }
...
}