…m calls (#7987)

Why I did it
Currently hostcfgd is implemented in a way each feature which is enabled/disabled triggering execution of systemctl enable/unmask commands which eventually trigger 'systemctl daemon-reload' command.
Each call like this cost 0.6s and overall add a overhead of ~12 seconds of CPU time.
This change will verify the desired state of a feature and the current state of this feature on systemd and trigger a system call only when must.

How I did it
Check each feature status on systemd before executing a system call to enable and reload the systemctl daemon.

How to verify it
Build an image with this change and observe less system calls are executed.

Signed-off-by: Shlomi Bitton <shlomibi@nvidia.com>