Add stop and down commands - #1339

Add devcontainer stop and devcontainer down

The README listed stop and down as planned but unimplemented. This PR adds both commands.

Usage

devcontainer stop [--workspace-folder | --container-id | --id-label <name=value>]
devcontainer down [--workspace-folder | --container-id | --id-label <name=value>] [--remove-volumes]

• stop stops the dev container. Running devcontainer up again restarts the same container.
• down stops the dev container and removes it.
• The container is found the same way exec finds it: via --container-id, --id-label, or --workspace-folder (plus optional --config). If none of these is given, --workspace-folder defaults to the current directory.
• Also supports --docker-path, --docker-compose-path, --log-level and --log-format.

Behavior

• Image / Dockerfile configs: stop runs docker stop <id>. down runs docker rm -f <id> through the existing removeContainer helper, which now takes an optional removeVolumes flag that adds -v.
• Docker Compose configs (detected via the com.docker.compose.project label): the commands run docker compose -p <project> stop|down, so every service in the project is handled.
  • With Compose v1 (docker-compose), the Compose files are passed with -f, taken from the container's com.docker.compose.project.config_files label.
• --remove-volumes (down only) removes anonymous volumes. For Compose configs it also removes named volumes declared in the Compose file (down -v).
• No matching container: the command logs Dev container not found. and exits with success. This makes down safe to run more than once.
• Output: on success, stdout gets a JSON line, consistent with the other commands:
  {"outcome":"success","containerId":"…","composeProjectName":"…"}

Changes

• src/spec-node/devContainersSpecCLI.ts: adds the stop and down commands and their shared options.
• src/spec-shutdown/dockerUtils.ts: removeContainer() takes an optional removeVolumes parameter (default false), so existing callers behave the same.
• README.md: marks stop and down as done and adds them to the command list.
• src/test/cli.stop-down.test.ts: new tests.

Tests

src/test/cli.stop-down.test.ts covers:

• image config: stop followed by up reuses the same container
• image config: down by --workspace-folder and by --container-id
• image config: down when the container has already been removed
• Compose config: stop and down for the whole project