MEDIUM: ssl/ckch: use ckch_store instead of ckch_data for ckch_conf_kws

MEDIUM: ssl/ckch: use ckch_store instead of ckch_data for ckch_conf_kws

This is an API change, instead of passing a ckch_data alone, the
ckch_conf_kws.func() is called with a ckch_store.

This allows the callback to access the whole ckch_store, with the
ckch_conf and the ckch_data. But it requires the ckch_conf to be
actually put in the ckch_store before.