Eeschema: fix incorrect display of the page number in a complex hierarchy.

When, inside a complex hierarchy, one switch from an instance of a sheet to an other instance of this sheet,
the page number shown in the worksheet was not updated on screen, and the initial number was displayed.

Fixes: lp:1827981
https://bugs.launchpad.net/kicad/+bug/1827981

eeschema/hierarch.cpp

@@ -290,5 +290,5 @@ void SCH_EDIT_FRAME::DisplayCurrentSheet()
     UpdateTitle();
 
     GetToolManager()->RunAction( SCH_ACTIONS::highlightNetSelection, true );
-    GetCanvas()->Refresh();
+    HardRedraw();   // Ensure any item has its view updated, especially the worksheet items
 }