Add more pubsub unittests

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxPython/Phoenix/trunk@73916 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix circular imports by delaying the import of framemanager in auibar and auibook until it is needed.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxPython/Phoenix/trunk@73917 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775