Add native NetworkManager support (#1224)

BZ: 2056964
Tested by: QA

commit feda344e6cf9d37b09bc13cf333a717d1654c26c
Author: Lubomir Rintel <lkundrak@v3.sk>
Date:   Fri Feb 25 23:33:20 2022 +0100

    Add native NetworkManager support (#1224)

    Fedora currently relies on sysconfig/ifcfg renderer. This is not too great,
    because Fedora (also RHEL since version 8) dropped support for the legacy
    network service that uses ifcfg files long ago.

    In turn, Fedora ended up patching cloud-init downstream to utilize
    NetworkManager's ifcfg compatibility mode [1]. This seems to have worked
    for a while, nevertheless the NetworkManager's ifcfg backend is reaching
    the end of its useful life too [2].

    [1] https://src.fedoraproject.org/rpms/cloud-init/blob/rawhide/f/cloud-init-21.3-nm-controlled.patch
    [2] https://fedoraproject.org/wiki/Changes/NoIfcfgFiles

    Let's not mangle things downstream and make vanilla cloud-init work great
    on Fedora instead.

    This also means that the sysconfig compatibility with
    Network Manager was removed.

    Firstly, this relies upon the fact that you can get ifcfg support by adding
    it to NetworkManager.conf. That is not guaranteed and certainly will not
    be case in future.

    Secondly, cloud-init always generates configuration with
    NM_CONTROLLED=no, so the generated ifcfg files are no good for
    NetworkManager. Fedora patches around this by just removing those lines
    in their cloud-init package.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>