overlay: create a dedicated thread for polling hotkeys (#864)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Create a new thread that polls for the following hotkeys:

* super exit (both alt+f4 and bound key)
* coin insert
* screenshot

The goal is to make the capture of these more reliable, because before
this PR it wasn't.

## Testing

src/spice2x/launcher/launcher.cpp

@@ -87,13 +87,13 @@
 #include "launcher/launcher.h"
 #include "launcher/logger.h"
 #include "launcher/signal.h"
-#include "launcher/superexit.h"
 #include "launcher/richpresence.h"
 #include "launcher/shutdown.h"
 #include "launcher/options.h"
 #include "misc/bt5api.h"
 #include "misc/device.h"
 #include "misc/eamuse.h"
+#include "misc/hotkeys.h"
 #include "misc/extdev.h"
 #include "misc/ami2000.h"
 #include "misc/sciunit.h"
@@ -1777,9 +1777,8 @@ int main_implementation(int argc, char *argv[]) {
         nvapi::initialize();
         // add application profile to nvcp
         nvapi::set_profile_settings();
-        // enable super exit
-        superexit::enable();
-
+        // keep ALT+F4 available during lengthy non-standalone boot
+        hotkeys::start();
         // enable subscreen touch emulation
         if (options[launcher::Options::spice2x_IIDXEmulateSubscreenKeypadTouch].is_active()) {
             games::iidx::ENABLE_POKE = true;
@@ -2452,6 +2451,7 @@ int main_implementation(int argc, char *argv[]) {
 
     // initialize raw input
     RI_MGR = std::make_unique<rawinput::RawInputManager>();
+    hotkeys::enable_raw_input();
     for (const auto &device : sextet_devices) {
         RI_MGR->sextet_register(device);
     }
@@ -2474,6 +2474,9 @@ int main_implementation(int argc, char *argv[]) {
     log_misc("rawinput", "Analog mappings:");
     dump_analog_bindings();
 
+    // mappings are ready; begin screenshot and coin polling during late startup
+    hotkeys::enable_input();
+
     // for certain games, show cursor if no touch is available (must be called after RI_MGR is available)
     if (show_cursor_if_no_touch && !is_touch_available("launcher::main_implementation")) {
         GRAPHICS_SHOW_CURSOR = true;
@@ -2703,9 +2706,6 @@ int main_implementation(int argc, char *argv[]) {
         API_CONTROLLER->listen_serial(api_serial_port[i], api_serial_baud[i]);
     }
 
-    // start coin input thread
-    eamuse_coin_start_thread();
-
     // pin macro
     if (!cfg::CONFIGURATOR_STANDALONE && PIN_MACRO_ENABLED) {
         eamuse_pin_macro_start_thread();
@@ -2755,6 +2755,9 @@ int main_implementation(int argc, char *argv[]) {
     log_info("launcher", "calling game entry");
     avs::game::entry_main();
 
+    // stop screenshot and coin polling; mapped SuperExit and ALT+F4 remain active
+    hotkeys::disable_input();
+
     // clear presence
     richpresence::shutdown();
 
@@ -2792,9 +2795,6 @@ int main_implementation(int argc, char *argv[]) {
     // free api controller
     API_CONTROLLER.reset();
 
-    // stop coin input thread
-    eamuse_coin_stop_thread();
-
     eamuse_pin_macro_stop_thread();
 
     // BT5API
@@ -2805,6 +2805,7 @@ int main_implementation(int argc, char *argv[]) {
     sdk::fini_sdk_modules();
 
     // stop raw input
+    hotkeys::disable_raw_input();
     RI_MGR.reset();
 
     // debug hook
@@ -2837,8 +2838,8 @@ int main_implementation(int argc, char *argv[]) {
     // dispose crypt
     crypt::dispose();
 
-    // disable super exit
-    superexit::disable();
+    // end early/late ALT+F4 monitoring at the same teardown point as legacy SuperExit
+    hotkeys::stop();
 
     // disable poke
     games::iidx::poke::disable();