Add AddressData and RouteData properties to NMSettingIPConfig and
NMIP[46]Config. These are like the existing "addresses" and "routes"
properties, but using strings and containing additional attributes,
like NMIPAddress and NMIPRoute.

This only affects the D-Bus representations; there are no API changes
to NMSettingIP{,4,6}Config or NMIP{4,6}Config as a result of this; the
additional information is just added to the existing 'addresses' and
'routes' properties.

NMSettingIP4Config and NMSettingIP6Config now always generate both
old-style data ('addresses', 'address-labels', 'routes') and new-style
data ('address-data', 'gateway', 'route-data') when serializing to
D-Bus, for backward compatibility. When deserializing, they will fill
in the 'addresses' and 'routes' properties from the new-style data if
it is present (ignoring the old-style data), or from the old-style
data if the new-style isn't present.

The daemon-side NMIP4Config and NMIP6Config always emit changes for
both 'Addresses'/'Routes' and 'AddressData'/'RouteData'. The
libnm-side classes initially listen for changes on both properties,
but start ignoring the 'Addresses' and 'Routes' properties once they
know the daemon is also providing 'AddressData' and 'RouteData'.