Kernel/Thread: move thread queue, current thread, and scheduling related function into the manager

As we touched it, remove IPC::GetCommandBuffer

src/core/arm/skyeye_common/armstate.cpp

@@ -604,7 +604,8 @@ void ARMul_State::ServeBreak() {
     if (last_bkpt_hit) {
         Reg[15] = last_bkpt.address;
     }
-    Kernel::Thread* thread = Kernel::GetCurrentThread();
+    Kernel::Thread* thread =
+        Core::System::GetInstance().Kernel().GetThreadManager().GetCurrentThread();
     Core::CPU().SaveContext(thread->context);
     if (last_bkpt_hit || GDBStub::GetCpuStepFlag()) {
         last_bkpt_hit = false;