The settings of NMConnectivity can change any time, by reloading the
configuration.

When reloading the configration, we don't want to interrupt or cancel
the pending reuqests, they should just complete with the old settings with
which they started. Note, that NMDevice is smart enough, that when a
newer request completes earlier, it invalidates all older, still pending
requests.

Anyway, that means, we cannot rely on the value to stay alive. Fix that,
by adding adding a new ref-counted struct for these parameters.

Fixes: 2cec94ba