- Each element of the (list) packageOperations needs to be a
package operation, which is a dictionary with keys (identifying actions)
and lists of packages (which may be strings or script-info dictionaries).
Package groups are divided into critical and non-critical
depending on whether we want all Calamares to fail if installing
a package in the group fails, or we are okay with just logging a
warning.
The distinction is configured in the YAML file listing the package
groups. By default, all groups are critical, to keep supporting
the previous behaviour.
