Add Pantalaimon support

This is actually authored by Julian Foad here
(https://lab.trax.im/matrix/matrix-docker-ansible-deploy), but was in
need of a rebase and various adjustments caused by huge playbook
refactoring that landed in the past months.

This rework is completely untested.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/266

roles/custom/matrix-pantalaimon/tasks/main.yml

@@ -0,0 +1,20 @@
+---
+
+- tags:
+    - setup-all
+    - setup-pantalaimon
+    - install-all
+    - install-pantalaimon
+  block:
+    - when: matrix_pantalaimon_enabled | bool
+      ansible.builtin.include_tasks: "{{ role_path }}/tasks/validate_config.yml"
+
+    - when: matrix_pantalaimon_enabled | bool
+      ansible.builtin.include_tasks: "{{ role_path }}/tasks/install.yml"
+
+- tags:
+    - setup-all
+    - setup-pantalaimon
+  block:
+    - when: not matrix_pantalaimon_enabled | bool
+      ansible.builtin.include_tasks: "{{ role_path }}/tasks/uninstall.yml"