- More code cleanup and codestyle updates

- Fixed some possible nullref exceptions
- Methods signatures now have up to 3 parameters before breakaing down each parameter in a separate line
- Method invocations have the same rule, except the first parameter will be in the same line as the invocation to prevent some ugliness when passing lambas as arguments
- Applied many more codestyles
- Extensions folder fully reformatted

src/NadekoBot/Services/Common/GreetGrouper.cs

@@ -6,9 +6,7 @@ public class GreetGrouper<T>
     private readonly object locker = new();
 
     public GreetGrouper()
-    {
-        group = new();
-    }
+        => group = new();
 
 
     /// <summary>