* Fix proxy and module_hotfixes

On CentOS 8 with proxy ansible render inline `proxy` and `module_hotfixes` options.

For example:

`proxy=http://127.0.0.1:3128module_hotfixes=True`

But expected result:

```
proxy=http://127.0.0.1:3128
module_hotfixes=True
```

* Use ini_file module for work with ini files

* Prevent duplicates proxy= option in /etc/yum.conf

Module `lineinfile` is weak, use most powerful module `ini_file` and add or remove `proxy=` when `http_proxy` is defined or not.