misc: Replace references to IntPtr/UIntPtr with nint/nuint + code cleanups.

src/ARMeilleure/Memory/IJitMemoryBlock.cs

@@ -4,7 +4,7 @@ namespace ARMeilleure.Memory
 {
     public interface IJitMemoryBlock : IDisposable
     {
-        IntPtr Pointer { get; }
+        nint Pointer { get; }
 
         void Commit(ulong offset, ulong size);
 

src/ARMeilleure/Memory/IMemoryManager.cs

@@ -6,7 +6,7 @@ namespace ARMeilleure.Memory
     {
         int AddressSpaceBits { get; }
 
-        IntPtr PageTablePointer { get; }
+        nint PageTablePointer { get; }
 
         MemoryManagerType Type { get; }
 

src/ARMeilleure/Memory/ReservedRegion.cs

@@ -8,7 +8,7 @@ namespace ARMeilleure.Memory
 
         public IJitMemoryBlock Block { get; }
 
-        public IntPtr Pointer => Block.Pointer;
+        public nint Pointer => Block.Pointer;
 
         private readonly ulong _maxSize;
         private readonly ulong _sizeGranularity;