Add nested list stories

[chrisvxd]

Description

This PR:

1. adds nested list stories to reproduce a bug causing items to be positioned incorrectly when dragging between nested droppables. You can reproduce this bug by dragging an item out of the list and into the root.
2. fixes a bug where droppables can collide with their own droppable children

Nested issues

1. Possible to collide with the droppable child of the currently dragged droppable (fixed by bd0c918, addressed in user-land by Puck)
2. General unstableness when dragging in-and-out of nested droppables (addressed in user-land by Puck)
3. Feedback plugin is spooked in this story with keyboard sensor
4. Dragging item outside of list causes a resize, but the calculation to offset this is now wrong. This is due to the reversal of the width / initialSize.width logic to account for iframes (fixed in
   cd400b1)

Other issues

1. Keyboard plugin doesn't work when dragging items out of iframes

[changeset-bot]

🦋 Changeset detected

Latest commit: d111206

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 7 packages

Name	Type
@dnd-kit/dom	Patch
@dnd-kit/react	Patch
@dnd-kit/abstract	Patch
@dnd-kit/collision	Patch
@dnd-kit/geometry	Patch
@dnd-kit/helpers	Patch
@dnd-kit/state	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[chrisvxd]

This comment could be clarified

Suggested change

	// Filter out collisions of items that contain other items
	// Filter out collisions of droppable children

[clauderic]

I would make this something like:

  @reactive
  public accessor parent: UniqueIdentifier | undefined;

  @derived
  public get path() {
    const {droppables} = manager.registry;
    const {parent} = this;
    const path = [];
    let parent = droppables.get(parent);
   
    while (parent) {
        path.push(parent.id);
        parent = droppables.get(parent.parent);
    }
    
    return path;
  }

And then the @dnd-kit/dom implementation can override path and automatically infer the path based on the DOM if this.parent is undefined

[chrisvxd]

I made it more abstract in d111206, but chose to override parent instead of path in the @dnd-kit/dom implementation so that .parent will still work. Let me know what you think.

[chrisvxd]

Had to rework this logic to account for regular size changes, too.

It seems to be mostly working, but keyboard sensor positions item a few px out, which has me suspicious