new module: AIX rootvg backup image using mksysb (#30460)
new module: AIX rootvg backup image using mksysb (#30460)

* new module: AIX rootvg backup image using mksysb

This module is simple but very useful for AIX system
administrators. Easy to construct playbooks to generate
and manage rootvg backups using mksysb tool.

* added module_check, pep8, non-written convention

- implemented module_check;
- fixed some pep8 and non-written convention

* removed parameters as global variables and doc

Moved global variables parameters to inside main()
Better doc format for mentioned files

thaim/ansible,thaim/ansible