IOS/USB: Emulate Wii Speak using cubeb

Based on @noahpistilli (Sketch) PR:
https://github.com/dolphin-emu/dolphin/pull/12567

Fixed the Windows support and the heisenbug caused by uninitialized
members.

Config system integration finalized.

Source/Core/AudioCommon/CubebUtils.cpp

@@ -72,3 +72,101 @@ std::shared_ptr<cubeb> CubebUtils::GetContext()
   weak = shared = {ctx, DestroyContext};
   return shared;
 }
+
+std::vector<std::pair<std::string, std::string>> CubebUtils::ListInputDevices()
+{
+  std::vector<std::pair<std::string, std::string>> devices;
+
+  cubeb_device_collection collection;
+  auto cubeb_ctx = CubebUtils::GetContext();
+  const int r = cubeb_enumerate_devices(cubeb_ctx.get(), CUBEB_DEVICE_TYPE_INPUT, &collection);
+
+  if (r != CUBEB_OK)
+  {
+    ERROR_LOG_FMT(AUDIO, "Error listing cubeb input devices");
+    return devices;
+  }
+
+  INFO_LOG_FMT(AUDIO, "Listing cubeb input devices:");
+  for (uint32_t i = 0; i < collection.count; i++)
+  {
+    const auto& info = collection.device[i];
+    const auto device_state = info.state;
+    const char* state_name = [device_state] {
+      switch (device_state)
+      {
+      case CUBEB_DEVICE_STATE_DISABLED:
+        return "disabled";
+      case CUBEB_DEVICE_STATE_UNPLUGGED:
+        return "unplugged";
+      case CUBEB_DEVICE_STATE_ENABLED:
+        return "enabled";
+      default:
+        return "unknown?";
+      }
+    }();
+
+    // According to cubeb_device_info definition in cubeb.h:
+    //  > "Optional vendor name, may be NULL."
+    // In practice, it seems some other fields might be NULL as well.
+    static constexpr auto fmt_str = [](const char* ptr) constexpr -> const char* {
+      return (ptr == nullptr) ? "(null)" : ptr;
+    };
+
+    INFO_LOG_FMT(AUDIO,
+                 "[{}] Device ID: {}\n"
+                 "\tName: {}\n"
+                 "\tGroup ID: {}\n"
+                 "\tVendor: {}\n"
+                 "\tState: {}",
+                 i, fmt_str(info.device_id), fmt_str(info.friendly_name), fmt_str(info.group_id),
+                 fmt_str(info.vendor_name), state_name);
+
+    if (info.device_id == nullptr)
+      continue;  // Shouldn't happen
+
+    if (info.state == CUBEB_DEVICE_STATE_ENABLED)
+    {
+      devices.emplace_back(info.device_id, fmt_str(info.friendly_name));
+    }
+  }
+
+  cubeb_device_collection_destroy(cubeb_ctx.get(), &collection);
+
+  return devices;
+}
+
+cubeb_devid CubebUtils::GetInputDeviceById(std::string_view id)
+{
+  if (id.empty())
+    return nullptr;
+
+  cubeb_device_collection collection;
+  auto cubeb_ctx = CubebUtils::GetContext();
+  const int r = cubeb_enumerate_devices(cubeb_ctx.get(), CUBEB_DEVICE_TYPE_INPUT, &collection);
+
+  if (r != CUBEB_OK)
+  {
+    ERROR_LOG_FMT(AUDIO, "Error enumerating cubeb input devices");
+    return nullptr;
+  }
+
+  cubeb_devid device_id = nullptr;
+  for (uint32_t i = 0; i < collection.count; i++)
+  {
+    const auto& info = collection.device[i];
+    if (id.compare(info.device_id) == 0)
+    {
+      device_id = info.devid;
+      break;
+    }
+  }
+  if (device_id == nullptr)
+  {
+    WARN_LOG_FMT(AUDIO, "Failed to find selected input device, defaulting to system preferences");
+  }
+
+  cubeb_device_collection_destroy(cubeb_ctx.get(), &collection);
+
+  return device_id;
+}