We should consider the distro configs such as centos-7-x86_64.cfg internal only and not user-configurable. However some of the options in the configs might be interesting to users so we should expose them elsewhere.

Acceptance criteria:

• the only two keys that a customer may need to change - kmods_to_ignore and releasever - are user-configurable in /etc/convert2rhel.ini
• the releasever key is removed from the distro configs altogether - we haven't documented it anywhere and we've only used it tests, so moving it from the distro config to the ini file won't be a breaking change
• the kmods_to_ignore in the distro is kept in the distro config and we introduce something like additional_kmods_to_ignore in the ini file
  • it would be worth verifying that on CentOS 7 the kernel/drivers/input/ff-memless.ko.xz kmod still causes troubles (it has moved to the kernel core and without ignoring it, the kmod check used to fail)
  • it's better to keep the kmods to ignore option in the distro config as it may happen that another occurence of kernel module being moved to kernel core happens and in that case we'd need to hardcode the kmod for the distro.