Next Generation Scenes

## Goal Description

Bevy needs a scene system that provides an ergonomic and friendly user facing API, supports code-driven and editor-driven workflows (in a way that is cross-compatible between the two use cases), is suitable for being the recommended API for composing Bevy UI and the upcoming Bevy Editor, supports inheritance, can construct scenes that read existing World state, and integrates cleanly with Bevy Assets. This should ultimately replace the current `bevy_scene` implementation.

## Goal Status

This is a potential [Bevy Project Goal](https://bevy.org/learn/contribute/project-information/project-goals/). Its state on the [Project Goals Board](https://github.com/orgs/bevyengine/projects/23/views/1) determines if it is Proposed, Postponed, Blocked (Approved), Inactive (Approved), Active (Approved), Completed, or Declined.

- **Staffing SMEs**: @cart
- **Working Group Link**: [link](https://discord.com/channels/691052431525675048/1264881140007702558)
- **Design Documents**: [Second Proposal](https://github.com/bevyengine/bevy/discussions/14437), [First Proposal](https://github.com/bevyengine/bevy/discussions/9538), [Draft PR](https://github.com/bevyengine/bevy/pull/20158)