Thread scheduler rewrite (#393)

* Started to rewrite the thread scheduler

* Add a single core-like scheduling mode, enabled by default

* Clear exclusive monitor on context switch

* Add SetThreadActivity, misc fixes

* Implement WaitForAddress and SignalToAddress svcs, misc fixes

* Misc fixes (on SetActivity and Arbiter), other tweaks

* Rebased

* Add missing null check

* Rename multicore key on config, fix UpdatePriorityInheritance

* Make scheduling data MLQs private

* nit: Ordering

Ryujinx.HLE/HOS/Kernel/ThreadSchedState.cs

@@ -0,0 +1,15 @@
+namespace Ryujinx.HLE.HOS.Kernel
+{
+    enum ThreadSchedState : byte
+    {
+        LowNibbleMask   = 0xf,
+        HighNibbleMask  = 0xf0,
+        ExceptionalMask = 0x70,
+        ForcePauseFlag  = 0x20,
+
+        None               = 0,
+        Paused             = 1,
+        Running            = 2,
+        TerminationPending = 3
+    }
+}