Undo Framework

## Goal Description

A generalized framework for handling undo / redo in Bevy. This should support:

* Simple use cases, such as pressing ctrl-Z while editing in a text input widget
* Complex use cases, such as deleting part of a scene in the Bevy scene editor
* Labeled actions, so that the "Undo" menu item can show something like "Undo Delete".

## 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**: Not yet staffed
- **Working Group Link**: Working Group not yet formed
- **Design Documents**: Design documents not yet written

Start with the Project Goals Board to determine whether this goal is Proposed, Postponed, Blocked, Inactive, Active, Completed, or Declined. No implementation files, tests, staffing, working group, or design documents are named; the work is not ready for a first contribution until the scope and design are established.

Written by the indexing model from the issue text.