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.

lib/ansible/modules/cloud/vultr/vr_firewall_group_facts.py

@@ -103,6 +103,9 @@ class AnsibleVultrFirewallGroupFacts(Vultr):
 
 
 def parse_fw_group_list(fwgroups_list):
+    if not fwgroups_list:
+        return []
+
     return [group for id, group in fwgroups_list.items()]
 
 

lib/ansible/modules/cloud/vultr/vr_ssh_key_facts.py

@@ -98,6 +98,9 @@ class AnsibleVultrSSHKeyFacts(Vultr):
 
 
 def parse_keys_list(keys_list):
+    if not keys_list:
+        return []
+
     return [key for id, key in keys_list.items()]
 
 

lib/ansible/modules/cloud/vultr/vr_startup_script_facts.py

@@ -102,6 +102,9 @@ class AnsibleVultrStartupScriptFacts(Vultr):
 
 
 def parse_startupscript_list(startupscipts_list):
+    if not startupscipts_list:
+        return []
+
     return [startupscript for id, startupscript in startupscipts_list.items()]