Restructured the project structure back to the way it was, there's no reasonable way to split the modules

src/NadekoBot/_common/Attributes/NadekoOptionsAttribute.cs

@@ -0,0 +1,7 @@
+namespace NadekoBot.Common.Attributes;
+
+[AttributeUsage(AttributeTargets.Method)]
+public sealed class NadekoOptionsAttribute<TOption> : Attribute
+    where TOption: INadekoCommandOptions
+{
+}