vmware_vm_facts: fix the support with regular ESXi

Ensure the module still work with the ESXi where CustomFieldsManager
does not exist.

From: https://www.vmware.com/support/developer/converter-sdk/conv60_apireference/vim.CustomFieldsManager.html

    The CustomFieldsManager object is used to add and remove custom fields to
    managed entities.
    The custom fields values set on managed entities are available through the
    customValue property and through the summary objects for VirtualMachine
    and HostSystem. They are not available directly through this managed object.
    This functionality is only available through VirtualCenter.

Fixes: #56071

test/integration/targets/vmware_vm_facts/tasks/main.yml

@@ -3,6 +3,15 @@
 # Copyright, (c) 2018, Fedor Vompe <f.vompe@comptek.ru>
 # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
 
+- when: vcsim is not defined
+  block:
+    - name: Get facts from a given ESXi
+      vmware_vm_facts:
+        validate_certs: false
+        hostname: '{{ esxi1 }}'
+        username: '{{ hostvars[esxi1].ansible_user }}'
+        password: '{{ hostvars[esxi1].ansible_password }}'
+
 - import_role:
     name: prepare_vmware_tests
   vars:
@@ -20,20 +29,22 @@
   register: vm_facts_0001
 
 - debug: var=vm_facts_0001
-- set_fact:
-    first_vm: "{{ vm_facts_0001['virtual_machines'][0] }}"
 
 - &vm_fact_check
   name: Verify if VM facts exist
   assert:
     that:
-      - first_vm.esxi_hostname is defined
-      - first_vm.guest_fullname is defined
-      - first_vm.ip_address is defined
-      - first_vm.mac_address is defined
-      - first_vm.power_state is defined
-      - first_vm.uuid is defined
-      - first_vm.vm_network is defined
+      - "item.esxi_hostname is defined"
+      - "item.guest_fullname is defined"
+      - "item.ip_address is defined"
+      - "item.mac_address is defined"
+      - "item.power_state is defined"
+      - "item.uuid is defined"
+      - "item.vm_network is defined"
+  with_items:
+    - "{{ vm_facts_0001.virtual_machines | json_query(query) }}"
+  vars:
+    query: "[?guest_name=='DC0_H0_VM0']"
 
 - <<: *vm_data
   name: Get facts about available vms in check mode
@@ -48,7 +59,7 @@
     hostname: "{{ vcenter_hostname }}"
     username: "{{ vcenter_username }}"
     password: "{{ vcenter_password }}"
-    name: "{{ first_vm.guest_name }}"
+    name: "DC0_H0_VM0"
   register: folder_path_info
 
 - set_fact:

test/units/module_utils/test_vmware.py

@@ -89,7 +89,9 @@ class FakeAnsibleModule:
 
 
 def fake_connect_to_api(module):
-    pass
+    class MyContent():
+        customFieldsManager = None
+    return MyContent
 
 
 def test_pyvmomi_lib_exists(mocker, fake_ansible_module):