IDebuggableProcess: Create and expose interface to enable implementation of debugging tools

# Conflicts:
#	src/ARMeilleure/State/DebugState.cs
#	src/ARMeilleure/State/ExecutionContext.cs
TODO: Fix comments. I also tried implementing AppleHV primitives here (it's actually broken).

src/Ryujinx.Cpu/IExecutionContext.cs

@@ -108,5 +108,10 @@ namespace Ryujinx.Cpu
         /// If you only need to pause the thread temporarily, use <see cref="RequestInterrupt"/> instead.
         /// </remarks>
         void StopRunning();
+
+        // TODO: comments
+        void DebugStop();
+        bool DebugStep();
+        void DebugContinue();
     }
 }