That is slightly complex, because we need to (DNS) resolve the endpoints,
and we also have to retry periodically. For example, initially we may be
unable to resolve an endpoint, but later we may be.
What is also interesting is that during assume and reapply, we may not
have all information in the profile. Most notably, the private keys will
be missing. We need to cope with that and not reconfigure keys. However,
we still need to resolve names and update the endpoints.
For now only add the core settings, no peers' data.
To support peers and the allowed-ips of the peers is more complicated
and will be done later. It's more complicated because these are nested
lists (allowed-ips) inside a list (peers). That is quite unusual and to
conveniently support that in D-Bus API, in keyfile format, in libnm,
and nmcli, is a effort.
Also, it's further complicated by the fact that each peer has a secret (the
preshared-key). Thus we probably need secret flags for each peer, which
is a novelty as well (until now we require a fixed set of secrets per
profile that is well known).
