Codespaces: Deep linking to specific samples

## Problem
Labs was designed to make it easy to view and run samples in the browser via GitHub Codespaces. We've succeeded on making that possible, but there are improvements that can be made regarding sample discovery:
- Right now, a user **must** load the entire repo in a Codespace, find the sample they want, and run it.
- If they want to see the source code, they **must** load the entire repo and find the files manually.

## Solution
As detailed in #19:
> Direct linking to specific samples may be possible, but it'll require some tinkering and research to nail down the setup
> - Separate folders can have a different devcontainer files. ([Configuring separate containers](https://code.visualstudio.com/remote/advancedcontainers/configure-separate-containers)).
> - Workspaces can be scoped to different folders.
> - You can link directly to a workspace in a codespace [like this](https://arlodotexe-michael-hawker-toolkit-labs-test.github.dev/?workspace=%2Fworkspaces%2FToolkit-Labs-Test%2F.devcontainer%2Fdefault.code-workspace) (see link format, clicking won't work anymore).