Auth lookup state cbdata upgrade

Auth lookup state cbdata upgrade

The authenticators utilize a "statedata" structure to store and pass
the callback and Auth::UserRequest an auth lookup is about.

This patch converts the structure from a CBDATA_GLOBAL_TYPE struct to a
CBDATA_CLASS2 and adds a parameterized constructor for it.

The result is that all the code using it no longer has to explicitly
manage fields assignments and cbdata referencing. Simply new the object
when submitting to the helper system and delete once its handler has
been called.