hle: kernel: k_memory_manager: Rework for latest kernel behavior.

- Updates the KMemoryManager implementation against latest documentation.
- Reworks KMemoryLayout to be accessed throughout the kernel.
- Fixes an issue with pool sizes being incorrectly reported.

src/core/hle/kernel/kernel.h

@@ -41,6 +41,7 @@ class KClientSession;
 class KEvent;
 class KHandleTable;
 class KLinkedListNode;
+class KMemoryLayout;
 class KMemoryManager;
 class KPort;
 class KProcess;
@@ -350,6 +351,9 @@ public:
     /// Gets the current worker task manager, used for dispatching KThread/KProcess tasks.
     const KWorkerTaskManager& WorkerTaskManager() const;
 
+    /// Gets the memory layout.
+    const KMemoryLayout& MemoryLayout() const;
+
 private:
     friend class KProcess;
     friend class KThread;