Examples: Fix top level build

Examples using the "shared" pattern need to be recorded in the list in
examples/quick/CMakeLists.txt, so that we do the necessary AUTOMOC
handling for them in a top level build. For details, see the commit
which introduced that list.
Amends 34bc389543.

Pick-to: 6.2
Change-Id: I6945b0c8445fe436da259dd240342e1c3b5cbf26
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Craig Scott <craig.scott@qt.io>

examples/quick/CMakeLists.txt

@@ -45,6 +45,7 @@ set(reused_dir_targets
     touchinteraction_shared
     window_shared
     shapes_shared
+    imageelements_shared
 )
 foreach(target IN LISTS reused_dir_targets)
     if(TARGET ${target})