added counting of connection state for sockets

[frenkye]

We had issue on one of our server, memcache was blocking some threads of FPM and they were stucked in "Finishing state"

This PR adding metriks like

# HELP php_fpm_state_count Count of PHP-FPM processes in each state.
# TYPE php_fpm_state_count gauge
php_fpm_state_count{socket_path="unix:///var/lib/php/8.1/fpm/test.cz.sock",state="Getting request information"} 3
php_fpm_state_count{socket_path="unix:///var/lib/php/8.1/fpm/test.cz.sock",state="Idle"} 28
php_fpm_state_count{socket_path="unix:///var/lib/php/8.1/fpm/test.cz.sock",state="Running"} 4

Based on info you get when calling

~$ REQUEST_METHOD="GET" SCRIPT_NAME="/fpm-status" SCRIPT_FILENAME="/fpm-status" QUERY_STRING="full" cgi-fcgi -bind -connect /var/lib/php/8.1/fpm/test.cz.sock

If something need to be modified, with a bit of guidance i can fix it.