ksys: Add more task utilities

* TaskMgr, ManagedTask, ManagedTaskHandle

* GameTaskThread: partial implementation because PhysicsMemSys / Havok
  stuff hasn't been decompiled yet and calc_() requires PhysicsMemSys

src/KingSystem/Utils/Thread/ManagedTaskHandle.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <basis/seadTypes.h>
+#include <time/seadTickSpan.h>
+#include "KingSystem/Utils/Types.h"
+
+namespace ksys::util {
+
+class ManagedTask;
+class TaskQueueBase;
+
+class ManagedTaskHandle {
+public:
+    enum class Status {
+        Uninitialized = 0,
+        TaskAttached = 1,
+        TaskFinished = 2,
+        TaskRemoved = 3,
+    };
+
+    ManagedTaskHandle();
+    virtual ~ManagedTaskHandle();
+
+    void finalize();
+
+    Status getStatus() const { return mStatus; }
+
+    void removeTaskFromQueue();
+    bool hasTask() const;
+
+    bool wait();
+    bool wait(const sead::TickSpan& wait_duration);
+
+    bool isTaskAttached() const;
+    bool didTaskCompleteSuccessfully() const;
+
+private:
+    friend class ManagedTask;
+
+    struct SetTaskArg {
+        ManagedTask* task;
+        TaskQueueBase* queue;
+    };
+
+    bool attachTask(const SetTaskArg& arg);
+    void setIsSuccess(bool success);
+    void setStatus(Status status);
+
+    void incrementRef_();
+    void decrementRef_();
+
+    bool mSuccess = false;
+    Status mStatus = Status::Uninitialized;
+    s32 mRefCount = 0;
+    ManagedTask* mTask = nullptr;
+    TaskQueueBase* mQueue = nullptr;
+};
+KSYS_CHECK_SIZE_NX150(ManagedTaskHandle, 0x28);
+
+}  // namespace ksys::util