core/memory: Migrate over Write{8, 16, 32, 64, Block} to the Memory class

The Write functions are used slightly less than the Read functions,
which make these a bit nicer to move over.

The only adjustments we really need to make here are to Dynarmic's
exclusive monitor instance. We need to keep a reference to the currently
active memory instance to perform exclusive read/write operations.

src/core/hle/kernel/mutex.cpp

@@ -117,7 +117,7 @@ ResultCode Mutex::Release(VAddr address) {
 
     // There are no more threads waiting for the mutex, release it completely.
     if (thread == nullptr) {
-        Memory::Write32(address, 0);
+        system.Memory().Write32(address, 0);
         return RESULT_SUCCESS;
     }
 
@@ -132,7 +132,7 @@ ResultCode Mutex::Release(VAddr address) {
     }
 
     // Grant the mutex to the next waiting thread and resume it.
-    Memory::Write32(address, mutex_value);
+    system.Memory().Write32(address, mutex_value);
 
     ASSERT(thread->GetStatus() == ThreadStatus::WaitMutex);
     thread->ResumeFromWait();