Expand system time selection logic

PluralKit.Bot/Utils.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Data;
 using System.Linq;
 using System.Net.Http;
@@ -9,6 +10,7 @@ using Discord.Commands;
 using Discord.Commands.Builders;
 using Discord.WebSocket;
 using Microsoft.Extensions.DependencyInjection;
+using NodaTime;
 using Image = SixLabors.ImageSharp.Image;
 
 namespace PluralKit.Bot