ProjectExplorer: Revive project importer

Fixes a regression introduced in recent changes. Import project from
build is now available again on the target setup page (shown when
no kit is active) and in the context menu of the left pane.

Task-number: QTCREATORBUG-17046
Change-Id: I5a1285624084f0cb6e0947560516ae88d4b3e376
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/projectexplorer/projectwindow.h

@@ -44,6 +44,7 @@ enum {
     ItemDeactivatedFromBelowRole, // A subitem got deactivated and gives us the opportunity to adjust
     ItemUpdatedFromBelowRole,     // A subitem got updated, re-expansion is necessary.
     ActiveItemRole,               // The index of the currently selected item in the tree view
+    KitIdRole,                    // The kit id in case the item is associated with a kit.
     PanelWidgetRole               // This item's widget to be shown as central widget.
 };