Dev Container for GitHub Copilot CLI with Codespaces, etc

### Describe the feature or problem you'd like to solve

Add a Dev Container for GitHub Copilot CLI with Codespaces, etc

### Proposed solution

I've been doing plenty of work with terminal coding agents inside of GitHub Codespaces [recently](https://github.com/asw101/codespaces) and I'd like to propose having a Codespace / Dev Container in this repo that allows folks to spin up a Codespace that has GitHub Copilot CLI pre-installed which I can run inside VS Code, especially via [Terminals in Editor Area](https://code.visualstudio.com/docs/terminal/basics#_terminals-in-editor-area).

### Example prompts or workflows

_No response_

### Additional context

_No response_