Let's make it possible to "suggest" that certain features or components
are enabled under some conditions.
For this, both features and components gain two things:
1. A Suggested= field which takes a boolean. If true the
feature/component will be suggested for installation, if false it
will not.
2. A set of SuggestedOnXYZ= settings are modelled after ConditionXYZ= in
unit files (and implement a subset of them), will suggest some
component/feature under specific conditions.
The result of the condition is shown in the various output tools.