* Auth: Add method `assertColumnRestrictions`
* ObjectSuggestions: Do not suggest protected variables
`assertColumnRestrictions` does not allow to use them
anymore, hence we should not suggest them in searches
as well to not to let the user run into an error by
accepting a suggestion. Though, when fetching values
as well, we still have to obfuscate, otherwise protected
vars won't show up in details anymore.
* Introduce Icinga\Module\Icingadb\Common\Model
Must be used as base for all models, to ensure
column restrictions are asserted on filters.
* Utilize `Icinga\Module\Icingadb\Common\Model` where applicable
