Fix "msg": "missing required arg: config_manager_text"

[NilashishC]

• Fixes "msg": "missing required arg: config_manager_text" #86
• Aligns docs and arguments to match other providers

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[trishnaguha]

If config_manager_file is passed, we would want to support config_manager_file also.

In load task:

- name: load configuration file contents
  set_fact:
    config_manager_text: "{{ lookup('config_template', config_manager_file) | join('\n') }}"
  when: config_manager_file is defined

[NilashishC]

@samccann fixed the docs issue you pointed to.

[samccann]

docs portion LGTM

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Build succeeded (gate pipeline).

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• dco-license : SUCCESS in 35s