## Type of Change
- [x] New feature
- [x] Breaking change
## Motivation and Context
This PR changes the behavior of the `defaultArguments` field in the
service plugin config. Previously, `defaultArguments` was functioning as
a way to indicate how to start a plugin in the event that the plugin is
loaded at boot (such as for the `container-core-images plugin`).
However, we now follow a convention where all plugins have a "start"
command that is used when launching the plugin, so this
`defaultArguments` field wasn't really providing much. Instead, there
are use cases where we may want to set default values to pass to a
plugin. This PR repurposes the `defaultArguments` field for those use
cases.
As an example use case, there are scenarios where someone may want to
use the AllocationOnlyVmnetNetwork even when running on macOS 26+. This
PR adds the ability to pass in a command line option to the vmnet
network plugin to specify that request. Combined with the
`defaultArguments` plugin config change, a user may choose to set that
field to ["--variant", "allocationOnly"] in the
`container-network-vmnet-config.json` to use AllocationOnlyVmnetNetwork
by default for all networks.
## Testing
- [x] Tested locally
- #859 added the traversal necessary to load the app bundle but forgot
to resolve symlinks. This fix adds the resolution, making it possible to
get default system properties from an app bundle Info.plist even if the
user invokes a command from, for example, `/usr/local/bin/container`
which is a symlink to the actual install path of the bundle.
- Also fixes bugs where an incorrect executable path was supplied in
some calls.
- Breaking change: `CommandLine.executablePathUrl` extension moved from
ContainerPlugin to ContainerVersion.
- This helps with brew cask packaging, can postflight link
libexec/container/plugins to the appropriate cask location, and the
plugin discovery will traverse the link.
- Sets up API server as source of truth for installation root, similarly
to what was done for the data root. `system start` establishes the
install root, setting the environment variable `CONTAINER_INSTALL_ROOT`
when launching the API server.
- The API server propagates the environment variable when launching
helpers, and returns the install root to the CLI via the health check
XPC.
- Includes several fixes for detecting plugins that use app bundle
layout.
Kathryn Baldauf