Add new parameter in order to switch firewall engine

Depends-On: https://review.opendev.org/c/openstack/tripleo-ansible/+/841414
Change-Id: If6fd1200629df555d5d9f007cd433da6eb1f952a

deployment/tripleo-firewall/tripleo-firewall-baremetal-ansible.yaml

@@ -33,6 +33,12 @@ parameters:
     type: json
     tags:
       - role_specific
+  FirewallEngine:
+    default: 'iptables'
+    description: Set the actual firewall engine. Can be "iptables" or "nftables"
+    type: string
+    constraints:
+      - allowed_values: ['iptables', 'nftables']
 
 resources:
   # Merging role-specific parameters (RoleParameters) with the default parameters.
@@ -69,6 +75,8 @@ outputs:
           - {get_attr: [RoleParametersValue, value, extra_firewall_rules]}
       host_firewall_tasks:
         - name: Run firewall role
+          vars:
+            tripleo_firewall_engine: {get_param: FirewallEngine}
           include_role:
             name: tripleo_firewall
       update_tasks:

releasenotes/notes/firewall-engine-36c6e6a9006fbad0.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Add a new parameter "FirewallEngine" in order to chose what firewall
+    engine we want to use. Values can be iptables (default), or nftables.