feat(packages): add package_version filter to ListGroupPackagesOptions

• Add PackageVersion to ListGroupPackagesOptions, matching the project options.
• Add OrderBy and Sort to ListPackageFilesOptions, matching the other package list options.
• Setting OrderBy/Sort here and the string fields on ListOptions at the same time would send duplicate keys. This matches the existing group and project package options.
• Tests: group list package_version, and package files order_by/sort sent exactly once.

Docs:

• https://docs.gitlab.com/api/packages/#for-a-group
• https://docs.gitlab.com/api/packages/#list-package-files