Change set_dhcp option to create nmconnection files for Redhat 9+

[fabi200123]

Currently when the set_dhcp option is set to true, it creates ifcfg files for all redhat versions.
From Rhel8, we also require to have the NM_CONTROLLED=yes, since in this version there is support for nmconnection files.
From Rhel9, it has changed from ifcfg files to nmconnection files, thus this PR adds a template and creates nmconnection files for all distros that have minimum version 9.

[Dany9966]

No. This is not what was asked. What was asked is to move the common methods from netpreserver into the osmorphing class, NOT the other way around. As the netpreservers are only meant to be used when actually setting up preservation, I'd like to not instantiate them when not actually needed, to avoid eventual spagetti code.

Please make sure you do the following for a proper refactor:

• Move all the code that will be used in both the osmorphing tool and netpreserver into osmorphing tool. (specifically what we need moved is: ifcfg._get_net_config_files, ifcfg._get_ifcfgs_by_type, nmconnection._get_nmconnection_files, nmconnection._get_keyfiles_by_type - it's alright if you move these to osmorphing.base);
• Inside netpreserver, use self.osmorphing_tool to reference those common methods;
• Make sure to ONLY use a netpreserver object inside of _setup_network_preservation, no other need for it.