Horizon: Implement arp:r and arp:w services (#5802)

* Horizon: Implement arp:r and arp:w services

* Fix formatting

* Remove HLE arp services

* Revert "Remove HLE arp services"

This reverts commit c576fcccadb963db56b96bacabd1c1ac7abfb1ab.

* Keep LibHac impl since it's used in bcat

* Addresses gdkchan's feedback

* ArpApi in PrepoIpcServer and remove LmApi

* Fix 2

* Fixes ArpApi init

* Fix encoding

* Update PrepoService.cs

* Fix prepo

src/Ryujinx.Horizon/Sdk/Arp/Detail/ApplicationInstanceManager.cs

@@ -0,0 +1,31 @@
+using Ryujinx.Horizon.Sdk.OsTypes;
+using System;
+using System.Threading;
+
+namespace Ryujinx.Horizon.Sdk.Arp.Detail
+{
+    class ApplicationInstanceManager : IDisposable
+    {
+        private int _disposalState;
+
+        public SystemEventType SystemEvent;
+        public int EventHandle;
+
+        public readonly ApplicationInstance[] Entries = new ApplicationInstance[2];
+
+        public ApplicationInstanceManager()
+        {
+            Os.CreateSystemEvent(out SystemEvent, EventClearMode.ManualClear, true).AbortOnFailure();
+
+            EventHandle = Os.GetReadableHandleOfSystemEvent(ref SystemEvent);
+        }
+
+        public void Dispose()
+        {
+            if (EventHandle != 0 && Interlocked.Exchange(ref _disposalState, 1) == 0)
+            {
+                Os.DestroySystemEvent(ref SystemEvent);
+            }
+        }
+    }
+}