Initial support for the new 12.x IPC system (#2182)

* Rename CommandAttribute as CommandHIpcAttribute to prepare for 12.x changes

* Implement inital support for TIPC and adds SM command ids

* *Ipc to *ipc

* Missed a ref in last commit...

* CommandAttributeTIpc to CommandAttributeTipc

* Addresses comment and fixes some bugs around

TIPC doesn't have any padding requirements as buffer C isn't a thing
Fix for RegisterService inverting two argument only on TIPC

Ryujinx.HLE/HOS/Services/CommandHIpcAttribute.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace Ryujinx.HLE.HOS.Services
+{
+    [AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
+    class CommandHipcAttribute : Attribute
+    {
+        public readonly int Id;
+
+        public CommandHipcAttribute(int id) => Id = id;
+    }
+}