CLI App Templates

## Goal Description

It should be possible to create new Bevy apps using a `bevy` CLI. There should be a standardized way to define new templates that are compatible with the `bevy` CLI.

## 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**: Currently unstaffed
- **Working Group Link**: [link](https://discord.com/channels/691052431525675048/1278871953721262090)
- **Design Documents**: [Bevy CLI Upstreaming Rationale](https://hackmd.io/y1J-r9y8TQClRjOEMeiQkA)