Move kernel state out of the Horizon class (#1107)

* Move kernel state from Horizon to KernelContext

* Merge syscalls partial classes, split 32 and 64-bit variants

* Sort usings

Ryujinx.HLE/HOS/Kernel/SupervisorCall/SyscallHandler.cs

@@ -0,0 +1,57 @@
+using ARMeilleure.State;
+using Ryujinx.HLE.HOS.Kernel.Threading;
+using System;
+
+namespace Ryujinx.HLE.HOS.Kernel.SupervisorCall
+{
+    partial class SyscallHandler
+    {
+        private readonly KernelContext _context;
+        private readonly Syscall32 _syscall32;
+        private readonly Syscall64 _syscall64;
+
+        public SyscallHandler(KernelContext context)
+        {
+            _context = context;
+            _syscall32 = new Syscall32(context.Syscall);
+            _syscall64 = new Syscall64(context.Syscall);
+        }
+
+        public void SvcCall(object sender, InstExceptionEventArgs e)
+        {
+            ExecutionContext context = (ExecutionContext)sender;
+
+            if (context.IsAarch32)
+            {
+                var svcFunc = SyscallTable.SvcTable32[e.Id];
+
+                if (svcFunc == null)
+                {
+                    throw new NotImplementedException($"SVC 0x{e.Id:X4} is not implemented.");
+                }
+
+                svcFunc(_syscall32, context);
+            }
+            else
+            {
+                var svcFunc = SyscallTable.SvcTable64[e.Id];
+
+                if (svcFunc == null)
+                {
+                    throw new NotImplementedException($"SVC 0x{e.Id:X4} is not implemented.");
+                }
+
+                svcFunc(_syscall64, context);
+            }
+
+            PostSvcHandler();
+        }
+
+        private void PostSvcHandler()
+        {
+            KThread currentThread = _context.Scheduler.GetCurrentThread();
+
+            currentThread.HandlePostSyscall();
+        }
+    }
+}