Add the option to add multiple ssh public keys for Azure infrastructure (#3674)

This give users the option to define multiple ssh public keys when
deploying the base infrastructure on Azure.

contrib/azurerm/roles/generate-templates/templates/bastion.json

@@ -66,10 +66,12 @@
             "disablePasswordAuthentication": "true",
             "ssh": {
               "publicKeys": [
+                {% for key in ssh_public_keys %}
                 {
                   "path": "{{sshKeyPath}}",
-                  "keyData": "{{ssh_public_key}}"
-                }
+                  "keyData": "{{key}}"
+                }{% if loop.index < ssh_public_keys | length %},{% endif %}
+                {% endfor %}
               ]
             }
           }