alerts: Improve DaemonSet rollout alert taking progress into account

[brancz]

Technically we also want to take observed generation into account, but there is currently no metric for this in kube-state-metrics and we'll want to wait a couple of releases after it's released to make use of that metric (see kubernetes/kube-state-metrics#1176).

Once observed generation is available, we can also add:

kube_daemonset_metadata_generation{%(prefixedNamespaceSelector)s%(kubeStateMetricsSelector)s}                                                                                                                                                                  
  ==
kube_daemonset_status_observed_generation{%(prefixedNamespaceSelector)s%(kubeStateMetricsSelector)s}

In the beginning, but this is already much improved. And I'll open an issue after this is merged to track that improvement.

@povilasv @metalmatze @tomwilkie @csmarchbanks

cc @beorn7 @pracucci as you recently improved many of the other apps API alerts

[beorn7]

I'm about to go on vacations and won't be able to have a detailed look in the next two weeks or so. Sorry...

[brancz]

I'm adding some tests and need to adapt the message of the alert as well so moving this to WIP for now.

[brancz]

Enjoy your vacation @beorn7!

For the rest, this is now ready for review :)

[povilasv]

This looks awesome 🥇