feat: add haproxy role

- add infra::halb section for highly available load balancers

site/roles/manifests/infra/halb/haproxy.pp

@@ -0,0 +1,5 @@
+# a role to deploy a haproxy node
+class roles::infra::halb::haproxy {
+  include profiles::defaults
+  include profiles::base
+}