Deprecate needs-restarting

[xsuchy]

The plugin needs-restarting has a naive implementation and gives users false hope that they get notified when system needs restarting. But that is not true when any dependence of running services is updated and the service needs to be restarted to load the newly updated library.

There is a much better plugin available https://dnf-plugins-extras.readthedocs.io/en/latest/tracer.html

I propose that we deprecate needs-restarting and point users that they should use dnf-plugins-extras-tracer.

I suggest two phases:

1. first, just print a warning that in future version this plugin will be removed.
2. After 12 months, make this warning fatal. But the plugin will still exists.
3. After the next 12 months, remove the plugin entirely.