- Closes#884.
## Type of Change
- [ ] Bug fix
- [x] New feature
- [ ] Breaking change
- [ ] Documentation update
## Motivation and Context
This PR implements the `container system df` command to display disk
usage statistics for images, containers, and volumes, along with their
total count, active count, size, and reclaimable space for each resource
type.
Active resources are determined by container mount references and
running state, while reclaimable space is calculated from inactive or
stopped resources.
Example output:
```
~/container ❯ container system df
TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 4 3 4.42 GB 516.5 MB (11%)
Containers 4 2 2.69 GB 1.51 GB (56%)
Local Volumes 3 2 208.5 MB 66.2 MB (32%)
```
I'll have some follow-on PRs that will add `-v/--verbose` flag for
detailed per-resource information, `--filter` flag for filtering output
by resource type, and a `--debug` flag for debug statistics like block
usage, clone counts etc.
## Testing
- [x] Tested locally
- [x] Added/updated tests
- [ ] Added/updated docs
- Part of #653.
- No need for `defaultCommand` since ContainerService startup will write
a new launchd plist with the `start` subcommand included.
## Type of Change
- [ ] Bug fix
- [ ] New feature
- [ ] Breaking change
- [ ] Documentation update
## Motivation and Context
Allows us to add commands to support post-installation, migration, etc.
## Testing
- [x] Tested locally
- [ ] Added/updated tests
- [ ] Added/updated docs
Today if you do system stop twice (or if you forgot the server isn't
running) you get bombarded with annoying (and confusing) XPC interrupted
messages. We should skip the container stop and list dance if we can't
talk to the APIServer with a simple ping.
