Configure /etc/default/useradd through 'defaults'

Add linux:system:defaults:user section that aims two things:

* configure /etc/default/useradd file as this file contains
  INACTIVE parameter that should be configured according to
  CIS 5.4.1.4
  We have to manage entire file so a template was added.

* Configure three parameters that are related to user
  account management but configured in /etc/login.defs file.
  These are PASS_MAX_DAYS, PASS_MIN_DAYS, PASS_WARN_AGE.

More details in README.rst

Related-Prod: PROD-23600

Change-Id: Idc502af3b0f31b3fe84dc9a42e3e9ec2ead7fe3c
6 files changed