Fix subelements conditional failure for filetree_create and object_diff

[adonisgarciac]

What does this PR do?

Loops with subelements were failing with error: "obj must be a list of dicts or a nested dict".

This was because subelement filter is executed before when and it was causing a failure when the list was not defined.

How should this be tested?

• name: test
  hosts: localhost
  gather_facts: false
  vars:
  __controller_api_current_user_check_is_admin:
  is_superuser: false

  tasks:
  - name: "Test nested condition"
  ansible.builtin.set_fact:
  __full_controller_api_roles: []
  loop: "{{ current_users | default([]) | subelements('organizations', skip_missing=true) }}"
  when: __controller_api_current_user_check_is_admin.is_superuser

[sean-m-sullivan]

needs to be rebased, and a line at end of file on the fragment.