Fix schematic editor crash when dragging symbols.

Do not set view items or update connectivity until after commit changes
are updated in the SCH_SREEN.  Updating the screen can force LIB_SYMBOL
changes which and lead to stale LIB_PIN object pointers stored in SCH_PIN
objects.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/16846

eeschema/sch_commit.cpp

@@ -509,7 +509,6 @@ void SCH_COMMIT::Revert()
                 view->Remove( item );
 
             item->SwapData( copy );
-            item->SetConnectivityDirty();
 
             // Special cases for items which have instance data
             if( item->GetParent() && item->GetParent()->Type() == SCH_SYMBOL_T
@@ -525,11 +524,14 @@ void SCH_COMMIT::Revert()
                 }
             }
 
+            // This must be called before any calls that require stable object pointers.
+            screen->Update( item );
+
+            item->SetConnectivityDirty();
+
             if( view )
                 view->Add( item );
 
-            screen->Update( item );
-
             delete copy;
             break;
         }