The DNS name can now also contain the DoT server name. It's not longer a
binary IP address only.

Extend NML3ConfigData to account for that. To track the additional
data, use the string representation. The alternative to have a separate
type that contains the parsed information would be cumbersome too.

It is almost always wrong, to split IPv4 and IPv6 behaviors at a high level.
Most of the code does something very similar. Combine the two functions.
and let them handle the difference closer to where it is.

For addresses that fail DAD we need to call nm_ndisc_dad_failed() to
generate a new address if addrgenmode is stable-privacy.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/1046

Instead of open coding the check for ready addresses, use
nm_l3cfg_check_ready().

It can be useful to know which addresses are conflicting, return them
from nm_l3cfg_check_ready().

Handle IP Configuration requests from IWD so that, when IWD's main.conf
setting [General].NetworkConfigurationEnabled is true, we don't try to
run DHCP or static addressing in parallel with IWD's internal DHCP or
static addressing.

Since part of the IWD secret agent and the new NetConfig agent
registration code is common, the agent object's path is changed.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1337

Fixes: 7bf46ced2e01 ('core/device: demote "strictly unamanged" error')