[Feature Request] S6 should read number of available CPUs and update the worker_processes directive in nginx config before starting nginx

[NickM-27]

Users running frigate may configure docker to a limited number of CPU cores. Nginx worker_processes auto directive creates a number of processes equal to the number of CPU cores (ignoring the cgroup limit). If the difference between available cores and configured cores is too large, nginx will spawn too many processes.

When starting nginx, the s6 process should read the number of available CPU cores from cgroups and adjust the worker_processes directive accordingly