WICKET-5759 AjaxRequestAttributes extra parameters aren't properly handled in getCallbackFunction()

(cherry picked from commit 8e00eb9f8ddae6d59950b33b6a2d38de27198886)
WICKET-5759 AjaxRequestAttributes extra parameters aren't properly handled in getCallbackFunction()

Fix test expectations

(cherry picked from commit e71ba640cd890fa27c1569ef3e02b265dbc9a980)
WICKET-5775 Replace the session upon successful signin for better support for Session Fixation

(cherry picked from commit 1a0953e9477d80e548431cd8eabec850c8d58ad9)