Create skeleton 'contained' exec

## Overview

In preparation for abstracting out some of the common setup logic used for locally hosted app-containers (e.g., a container that runs Chrome, Atom, a development suite, or provides local tools and services), we're going to create a skeleton CLI.

## Deliverables

* [ ] Create `src/cli/contained.sh`. This will be our contained management tool.
* [ ] Put in skeleton support for (see ['contained setup'](#contained-setup)):
* `describe`
* `list`
* `run`
* `stop`
* `import`
* `forget`
* [ ] We will also have a second command group `dev` with actions:
* `describe`
* `build`
* `publish`
* `run`
* `stop`
* `setup`

Start with the requested path, src/cli/contained.sh, and inspect the repository for existing CLI conventions before defining the skeleton. Done means the tool exists with the contained actions describe, list, run, stop, import, and forget, plus the dev actions describe, build, publish, run, stop, and setup.

Written by the indexing model from the issue text.