Proxy fixes (#5869)

* 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.

roles/container-engine/docker/templates/rh_docker.repo.j2

@@ -6,4 +6,5 @@ gpgcheck={{ '1' if docker_rh_repo_gpgkey else '0' }}
 keepcache={{ docker_rpm_keepcache | default('1') }}
 gpgkey={{ docker_rh_repo_gpgkey }}
 {% if http_proxy is defined %}proxy={{ http_proxy }}{% endif %}
+
 {% if ansible_os_family == "RedHat" and ansible_distribution_major_version|int == 8 %}module_hotfixes=True{% endif %}