Refactor memory managers to a common base class, consolidate Read() method logic (#6360)

* - add new abstract class `VirtualMemoryManagerBase`
- rename `MemoryManagerBase` to `VirtualMemoryManagerRefCountedBase` and derive from `VirtualMemoryManagerBase`
- change `AddressSpaceManager`, `HvMemoryManager`, `MemoryManager`, and `MemoryManagerHostMapped` to implement abstract members and use the inherited `void VirtualMemoryManagerBase.Read(TVirtual va, Span<byte> data)` implementation.

* move property `AddressSpaceSize` up by the other properties

src/Ryujinx.Cpu/MemoryManagerBase.cs

@@ -1,32 +0,0 @@
-using Ryujinx.Memory;
-using System.Diagnostics;
-using System.Threading;
-
-namespace Ryujinx.Cpu
-{
-    public abstract class MemoryManagerBase : IRefCounted
-    {
-        private int _referenceCount;
-
-        public void IncrementReferenceCount()
-        {
-            int newRefCount = Interlocked.Increment(ref _referenceCount);
-
-            Debug.Assert(newRefCount >= 1);
-        }
-
-        public void DecrementReferenceCount()
-        {
-            int newRefCount = Interlocked.Decrement(ref _referenceCount);
-
-            Debug.Assert(newRefCount >= 0);
-
-            if (newRefCount == 0)
-            {
-                Destroy();
-            }
-        }
-
-        protected abstract void Destroy();
-    }
-}