feat: upgrade to .NET 6, refactor everything

PluralKit.Bot/CommandSystem/CommandGroup.cs

@@ -1,19 +1,16 @@
-using System.Collections.Generic;
+namespace PluralKit.Bot;
 
-namespace PluralKit.Bot
+public class CommandGroup
 {
-    public class CommandGroup
+    public CommandGroup(string key, string description, ICollection<Command> children)
     {
-        public string Key { get; }
-        public string Description { get; }
-
-        public ICollection<Command> Children { get; }
-
-        public CommandGroup(string key, string description, ICollection<Command> children)
-        {
-            Key = key;
-            Description = description;
-            Children = children;
-        }
+        Key = key;
+        Description = description;
+        Children = children;
     }
+
+    public string Key { get; }
+    public string Description { get; }
+
+    public ICollection<Command> Children { get; }
 }