Texture Dumping: Show OSD message on startup and when toggled

If texture dumping is enabled, notify the user on emulation startup
using an On Screen Display message.

Also notify the user when texture dumping is toggled.

Addresses https://bugs.dolphin-emu.org/issues/12445.

Source/Core/DolphinQt/HotkeyScheduler.cpp

@@ -469,7 +469,14 @@ void HotkeyScheduler::Run()
       }
 
       if (IsHotkey(HK_TOGGLE_DUMPTEXTURES))
-        Config::SetCurrent(Config::GFX_DUMP_TEXTURES, !Config::Get(Config::GFX_DUMP_TEXTURES));
+      {
+        const bool enable_dumping = !Config::Get(Config::GFX_DUMP_TEXTURES);
+        Config::SetCurrent(Config::GFX_DUMP_TEXTURES, enable_dumping);
+        OSD::AddMessage(
+            fmt::format("Texture Dumping {}",
+                        enable_dumping ? "enabled. This will reduce performance." : "disabled."),
+            OSD::Duration::NORMAL);
+      }
 
       if (IsHotkey(HK_TOGGLE_TEXTURES))
         Config::SetCurrent(Config::GFX_HIRES_TEXTURES, !Config::Get(Config::GFX_HIRES_TEXTURES));

Source/Core/VideoCommon/VideoBackendBase.cpp

@@ -52,6 +52,7 @@
 #include "VideoCommon/GeometryShaderManager.h"
 #include "VideoCommon/GraphicsModSystem/Runtime/GraphicsModManager.h"
 #include "VideoCommon/IndexGenerator.h"
+#include "VideoCommon/OnScreenDisplay.h"
 #include "VideoCommon/OpcodeDecoding.h"
 #include "VideoCommon/PixelEngine.h"
 #include "VideoCommon/PixelShaderManager.h"
@@ -392,6 +393,12 @@ bool VideoBackendBase::InitializeShared(std::unique_ptr<AbstractGfx> gfx,
   g_Config.VerifyValidity();
   UpdateActiveConfig();
 
+  if (g_Config.bDumpTextures)
+  {
+    OSD::AddMessage(fmt::format("Texture Dumping is enabled. This will reduce performance."),
+                    OSD::Duration::NORMAL);
+  }
+
   g_shader_cache->InitializeShaderCache();
 
   return true;