Support Flatcar and provide ignition bootstrap data

[mcbenjemaa]

This PR:

• flatcar and ignition support
• Add networkd units support for flatcar

fixes #302

[mcbenjemaa]

Creation of cluster and upgrades works seamlessly 🟢

k --kubeconfig test-3 get nodes -owide
NAME                         STATUS   ROLES           AGE     VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE                                             KERNEL-VERSION   CONTAINER-RUNTIME  ok  kind-playground kube 
test-3-control-plane-4qmdg   Ready    control-plane   5m45s   v1.31.1   10.4.18.154   <none>        Flatcar Container Linux by Kinvolk 4081.1.0 (Oklo)   6.6.54-flatcar   containerd://1.7.20
test-3-control-plane-5kjkd   Ready    control-plane   7m36s   v1.31.1   10.4.18.152   <none>        Flatcar Container Linux by Kinvolk 4081.1.0 (Oklo)   6.6.54-flatcar   containerd://1.7.20
test-3-control-plane-lrxhw   Ready    control-plane   10m     v1.31.1   10.4.18.159   <none>        Flatcar Container Linux by Kinvolk 4081.1.0 (Oklo)   6.6.54-flatcar   containerd://1.7.20
test-3-workers-pvjnx-49x8v   Ready    node            10m     v1.31.1   10.4.18.158   <none>        Flatcar Container Linux by Kinvolk 4081.1.0 (Oklo)   6.6.54-flatcar   containerd://1.7.20
test-3-workers-pvjnx-hcfbr   Ready    node            5m8s    v1.31.1   10.4.18.155   <none>        Flatcar Container Linux by Kinvolk 4081.1.0 (Oklo)   6.6.54-flatcar   containerd://1.7.20
test-3-workers-pvjnx-s2sll   Ready    node            7m8s    v1.31.1   10.4.18.153   <none>        Flatcar Container Linux by Kinvolk 4081.1.0 (Oklo)   6.6.54-flatcar   containerd://1.7.20

[mcbenjemaa]

I don't see any difference between whether to use the function pointer.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
86.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud