refactor(main): move remaining entry related code (#2127)

src/globals.h

@@ -0,0 +1,42 @@
+/**
+ * @file globals.h
+ * @brief Header for globally accessible variables and functions.
+ */
+#pragma once
+
+#include "entry_handler.h"
+#include "thread_pool.h"
+
+extern thread_pool_util::ThreadPool task_pool;
+extern bool display_cursor;
+
+#ifdef _WIN32
+  // Declare global singleton used for NVIDIA control panel modifications
+  #include "platform/windows/nvprefs/nvprefs_interface.h"
+extern nvprefs::nvprefs_interface nvprefs_instance;
+#endif
+
+namespace mail {
+#define MAIL(x)                         \
+  constexpr auto x = std::string_view { \
+    #x                                  \
+  }
+
+  extern safe::mail_t man;
+
+  // Global mail
+  MAIL(shutdown);
+  MAIL(broadcast_shutdown);
+  MAIL(video_packets);
+  MAIL(audio_packets);
+  MAIL(switch_display);
+
+  // Local mail
+  MAIL(touch_port);
+  MAIL(idr);
+  MAIL(invalidate_ref_frames);
+  MAIL(gamepad_feedback);
+  MAIL(hdr);
+#undef MAIL
+
+}  // namespace mail