Add possibility to additional configuration of the main context

[realmyst]

Now we can add more options to main config context, e.g.:

user www-data  www-data;
worker_processes  auto;
pid /var/run/nginx.pid;
worker_rlimit_nofile 1024;
include /etc/nginx/modules-enabled/*.conf; # extra option

http {
...
}

[jdauphant]

Thanks for the MR.
I have made one comment

[jdauphant]

nginx_extra_params
Maybe we can make this more explicit like "nginx_extra_root_params" or "nginx_extra_top_params"

[realmyst]

Yes, I agree that nginx_extra_root_params would be more explicit. Renamed it.

[jdauphant]

Merged and release in 2.4

[jdauphant]

@realmyst I didn't see it before merging but could have been nice if it was a list instead of a single string attribute