playbook/vm-bootstrap: Ensure network availability

While bootstraping a host, the network can be in unknown state, and a
lot of tasks depend on the network, thus make sure that network is
available.

By extracting the hostname task to vm-bootstrap-hostname it's possible
to setup it as a dependency role for vm-bootstrap, before package role,
which depends on the network setup.

playbook/roles/vm-bootstrap/tasks/resolv_conf_systemd.yml → playbook/roles/vm-bootstrap-hostname/tasks/resolv_conf_systemd.yml

   - name: configuring systemd-resolved (add search)
     lineinfile: dest=/etc/systemd/resolved.conf line="Domains=tl.teralab-datascience.fr"
+    notify: restart systemd-resolved
 
   - name: configuring systemd-resolved (add DNS)
     lineinfile: dest=/etc/systemd/resolved.conf line="DNS=10.200.218.1"
+    notify: restart systemd-resolved
 
   - name: configuring systemd-resolved (no FallbackDNS)
     lineinfile: dest=/etc/systemd/resolved.conf line="FallbackDNS="
     notify: restart systemd-resolved
+
+  - name: Ensure resolved is restarted
+    meta: flush_handlers

playbook/roles/vm-bootstrap/meta/main.yml

 ---
 dependencies:
+  - { role: vm-bootstrap-hostname }
   - { role: package, package_name: python3, package_state: present }

playbook/roles/vm-bootstrap/tasks/main.yml

@@ -42,7 +42,6 @@
     register: upgrade_needed
 
   - include: network.yml
-  - include: hostname.yml
   - include: user.yml
   - include: ssh.yml