msmtp(role): introduce msmtp role

Introduce msmtp role for setting up msmtp for mail sending.
Also add accompanying host group and playbook play.

roles/msmtp/tasks/main.yaml

@@ -0,0 +1,14 @@
+- name: ensure msmtp is installed
+  ansible.builtin.apt:
+    name: msmtp
+    state: present
+  become: true
+
+- name: ensure msmtp config for root user
+  ansible.builtin.template:
+    src: msmtprc.j2
+    dest: /root/.msmtprc
+    owner: root
+    group: root
+    mode: "0600"
+  become: true