SpecialPage::getDescription is key here

	 * Returns the name that goes in the \<h1\> in the special page itself, and
	 * also the name that will be listed in Special:Specialpages

The getDescription method for the relevant special pages should be overridden to allow for use of a different description when federated properties is enabled.
(description in this context has nothing to do with wikibase descriptions)

Entity types (we need item) also already have i18n values.

	"wikibase-entity-item": "Item",

A decision for the implementor would be to decide if:

• Some IF condition goes in the special pages switching on the config
• Some message prefix (or the whole message?) is injected

Acceptance Criteria:

• SetLabel done
• SetDescription done
• SetAliases done
• SetLabelDescriptionAliases done
• Paramertized message (for entity types) rather than hardcoding the "Item" type into the string.