feat: implement devcontainer stop and down commands

- Add 'devcontainer stop' command to stop running containers
- Add 'devcontainer down' command to stop and remove containers
- Support --all flag to target all devcontainers
- Support --workspace-folder to target specific workspace
- Support --id-label for custom label filtering
- Support --remove-volumes for down command
- Update README.md to mark both commands as completed
- Handle both single container and Docker Compose configurations

Author: monotykamary

README.md

@@ -17,8 +17,8 @@ This CLI is in active development. Current status:
 - [x] `devcontainer exec` - Executes a command in a container with `userEnvProbe`, `remoteUser`, `remoteEnv`, and other properties applied
 - [x] `devcontainer features <...>` - Tools to assist in authoring and testing [Dev Container Features](https://containers.dev/implementors/features/)
 - [x] `devcontainer templates <...>` - Tools to assist in authoring and testing [Dev Container Templates](https://containers.dev/implementors/templates/)
-- [ ] `devcontainer stop` - Stops containers
-- [ ] `devcontainer down` - Stops and deletes containers
+- [x] `devcontainer stop` - Stops containers
+- [x] `devcontainer down` - Stops and deletes containers
 
 ## Try it out
 
@@ -44,6 +44,8 @@ Commands:
   devcontainer read-configuration   Read configuration
   devcontainer features             Features commands
   devcontainer templates            Templates commands
+  devcontainer stop                 Stop dev containers
+  devcontainer down                 Stop and remove dev containers
   devcontainer exec <cmd> [args..]  Execute a command on a running dev container
 
 Options: