Rework DNS stack to meet hostnet pods needs

* For Debian/RedHat OS families (with NetworkManager/dhclient/resolvconf
  optionally enabled) prepend /etc/resolv.conf with required nameservers,
  options, and supersede domain and search domains via the dhclient/resolvconf
  hooks.

* Drop (z)nodnsupdate dhclient hook and re-implement it to complement the
  resolvconf -u command, which is distro/cloud provider specific.
  Update docs as well.

* Enable network restart to apply and persist changes and simplify handlers
  to rely on network restart only. This fixes DNS resolve for hostnet K8s
  pods for Red Hat OS family. Skip network restart for canal/calico plugins,
  unless https://github.com/projectcalico/felix/issues/1185 fixed.

* Replace linefiles line plus with_items to block mode as it's faster.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Co-authored-by: Matthew Mosesohn <mmosesohn@mirantis.com>

roles/kubernetes/preinstall/tasks/dhclient-hooks.yml

@@ -0,0 +1,33 @@
+---
+- name: Configure dhclient to prepend nameservers and supersede search/domain
+  blockinfile:
+    block: |-
+      {% for item in [ supersede_domain, supersede_search, prepend_nameserver ] -%}
+      {{ item }}
+      {% endfor %}
+    dest: "{{dhclientconffile}}"
+    create: yes
+    state: present
+    insertbefore: BOF
+    backup: yes
+    follow: yes
+    marker: "# Ansible entries {mark}"
+  notify: Preinstall | restart network
+
+- name: Configue dhclient hooks for resolv.conf (non-RH)
+  template:
+    src: dhclient_dnsupdate.sh.j2
+    dest: "{{ dhclienthookfile }}"
+    owner: root
+    mode: 0755
+  notify: Preinstall | restart network
+  when: ansible_os_family != "RedHat"
+
+- name: Configue dhclient hooks for resolv.conf (RH-only)
+  template:
+    src: dhclient_dnsupdate_rh.sh.j2
+    dest: "{{ dhclienthookfile }}"
+    owner: root
+    mode: 0755
+  notify: Preinstall | restart network
+  when: ansible_os_family == "RedHat"