Packages.rb - added product upgrade summary functions (bnc#883047)

- 3.1.24

(Note: the methods will be used in `yast2-update`.)
maybe better have quick end like
```
# no automatic removed => no warning
return {} if status[:removed].none? { |product| product["transact_by"] == :solver }

{
  "warning_level" => :blocker,
  "warning"          => _( ...
}
end
```