feat: Implement audio backend and APU debugging features

- Introduced a new audio backend system with SDL2 support, allowing for flexible audio management and improved performance.
- Added APU handshake tracking capabilities to monitor CPU-APU communication during audio program uploads, enhancing debugging and transfer diagnostics.
- Updated the Emulator class to integrate the new audio backend, ensuring compatibility with existing audio handling.
- Implemented an APU Debugger UI for real-time monitoring of handshake status, port activity, and transfer progress, improving user experience for debugging audio issues.
- Refactored audio-related code to streamline audio sample queuing and management, enhancing overall emulator performance.

src/CMakeLists.txt

@@ -1,12 +1,14 @@
 set(
   YAZE_APP_EMU_SRC
   app/emu/audio/apu.cc
+  app/emu/audio/audio_backend.cc
   app/emu/audio/spc700.cc
   app/emu/audio/dsp.cc
   app/emu/audio/internal/addressing.cc
   app/emu/audio/internal/instructions.cc
   app/emu/cpu/internal/addressing.cc
   app/emu/cpu/internal/instructions.cc
+  app/emu/debug/apu_debugger.cc
   app/emu/debug/disassembly_viewer.cc
   app/emu/debug/breakpoint_manager.cc
   app/emu/debug/watchpoint_manager.cc
@@ -884,6 +886,8 @@ source_group("Application\\Emulator" FILES
 source_group("Application\\Emulator\\Audio" FILES
   app/emu/audio/apu.cc
   app/emu/audio/apu.h
+  app/emu/audio/audio_backend.cc
+  app/emu/audio/audio_backend.h
   app/emu/audio/spc700.cc
   app/emu/audio/spc700.h
   app/emu/audio/dsp.cc
@@ -920,6 +924,18 @@ source_group("Application\\Emulator\\Video" FILES
   app/emu/video/ppu_registers.h
 )
 
+# Debug System
+source_group("Application\\Emulator\\Debug" FILES
+  app/emu/debug/apu_debugger.cc
+  app/emu/debug/apu_debugger.h
+  app/emu/debug/breakpoint_manager.cc
+  app/emu/debug/breakpoint_manager.h
+  app/emu/debug/disassembly_viewer.cc
+  app/emu/debug/disassembly_viewer.h
+  app/emu/debug/watchpoint_manager.cc
+  app/emu/debug/watchpoint_manager.h
+)
+
 # Graphics System
 source_group("Application\\Graphics" FILES
   app/gfx/arena.cc