Vultr: Ensure facts works when no resource exists (#43603)

Vultr API is being inconsisten in what it returns. An empty list when no
resources exists, but a dict of dict when they do. The case needs to be
handled so the module do not fail. An extra test has been added.

test/legacy/roles/vr_firewall_group_facts/tasks/main.yml

@@ -1,6 +1,9 @@
 # Copyright (c) 2018, Yanis Guenane <yanis+ansible@guenane.org>
 # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
 ---
+- name: test gather vultr firewall group facts - empty resources
+  vr_firewall_group_facts:
+
 - name: Create the firewall group
   vr_firewall_group:
     name: '{{ firewall_group_name }}'

test/legacy/roles/vr_ssh_key_facts/tasks/main.yml

@@ -1,6 +1,9 @@
 # Copyright (c) 2018, Yanis Guenane <yanis+ansible@guenane.org>
 # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
 ---
+- name: test gather vultr ssh key fact - empty resources
+  vr_ssh_key_facts:
+
 - name: Upload an ssh key
   vr_ssh_key:
     name: '{{ ssh_key_name }}'

test/legacy/roles/vr_startup_script_facts/tasks/main.yml

@@ -1,6 +1,9 @@
 # Copyright (c) 2018, Yanis Guenane <yanis+ansible@guenane.org>
 # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
 ---
+- name: test gather vultr startup script facts - empty resources
+  vr_startup_script_facts:
+
 - name: Create the script
   vr_startup_script:
     name: '{{ startup_script_name }}'