Add UTC option to FormatTime

[sirdigbot]

Resolves #875

Tested with the following code and https://www.epochconverter.com/

#include <sourcemod>

public void OnPluginStart()
{
    char time[32];
    
    PrintToServer("Now: %i", GetTime());
    
    FormatTime(time, sizeof(time), "%Y-%m-%d %H:%M:%S", 0);
    PrintToServer("Local time 0: %s", time);
    
    FormatTime(time, sizeof(time), "%Y-%m-%d %H:%M:%S", 0, false); 
    PrintToServer("UTC time 0: %s", time);
    
    FormatTime(time, sizeof(time), "%Y-%m-%d %H:%M:%S");
    PrintToServer("Local time now: %s", time);
    
    FormatTime(time, sizeof(time), "%Y-%m-%d %H:%M:%S", -1, false);
    PrintToServer("UTC time now: %s", time);

    // OUTPUTS:
    // Now: 1660197444
    // Local time 0: 1970-01-01 11:00:00
    // UTC time 0: 1970-01-01 00:00:00
    // Local time now: 2022-08-11 15:57:24
    // UTC time now: 2022-08-11 05:57:24
}

[sirdigbot]

I never saw it because I guess it wasn't linked to the issue, but PR #917 addresses the same thing

[sapphonie]

Any updates on this?