[#163] Add internal network traffic metrics

[An-DJ]

Add new network traffic panels in the dashboard and the following metrics:

• pgagroal_network_sent
• pgagroal_network_received

Modify the spelling of some words in the dashboard.

[jesperpedersen]

Why not _add(ssize_t) ?

[An-DJ]

Why not _add(ssize_t) ?

Yeah, it's a little bit more concise. I have modified the code just now.

[jesperpedersen]

Yeah, that looks better - maybe name them network_sent and network_receive in the function names as well

[jesperpedersen]

Also name the parameter, as

/**
 * Increase network_sent
 * @param s The size
 * /
void pgagroal_prometheus_network_sent(ssize_t s);

[An-DJ]

Also name the parameter, as

/**
 * Increase network_sent
 * @param s The size
 * /
void pgagroal_prometheus_network_sent(ssize_t s);

Done.

[jesperpedersen]

Better do it in prometheus.c and the Grafana file as well

[An-DJ]

Better do it in prometheus.c and the Grafana file as well

Done.

[jesperpedersen]

Thanks for your contribution !