aarch64/mem: Introduce a dedicated guest memory access layer

This commit introduces a proper abstraction layer for all read and write
operations.

The previous approach of directly calculating a Host Virtual Address
(HVA) from a Guest Physical Address (GPA) via gpa_to_hva() forces every
part of the emulator that touches guest memory to be aware of the
underlying host pointer, which is poor design.

This new layer introduces a suite of guest_mem_read{b,w,l,q} and
guest_mem_write{b,w,l,q} fuctions. All future memory accesses from the
emulated CPU should be performed through these functions.

The code has also been moved into the pound::aarch64 namespace for
better organization.

Signed-off-by: Ronald Caesar <github43132@proton.me>

core/Base/Logging/Filter.cpp

@@ -68,6 +68,7 @@ bool ParseFilterRule(Filter &instance, Iterator begin, Iterator end) {
   CLS(System)                                                                                    \
   CLS(Render)                                                                                    \
   CLS(ARM)                                                                                       \
+  CLS(Memory)                                                                                    \
 
 // GetClassName is a macro defined by Windows.h, grrr...
 const char* GetLogClassName(Class logClass) {

core/Base/Logging/LogTypes.h

@@ -34,6 +34,7 @@ enum class Class : const u8 {
   System,                 // Base System messages
   Render,                 // OpenGL and Window messages
   ARM,
+  Memory,
   Count                   // Total number of logging classes
 };