apb run defined empty parameters

[ruromero]

As an APB developer I would like apb run to behave the same as the UI. If a parameter is intentionally left empty it is defined and its value is "" (empty string) which requires the developer to be aware of this behaviour.

E.g.

my_pwd: "{{ apb_my_pwd | default('foo') }}"

This is the typical way of checking a variable is defined. The outcome will be "" if executed through apb run and generated using the UI.

Although is easy to workaround by setting the true parameter to the default filter it can get more complex in some other situations:

{% if apb_my_pwd %}

- set_fact:
    my_fact: "test"
  when: !apb_my_pwd