[hle,display,overlay,starter,hid] add overlay functions, starter applet (initially), HID handheld for system applets and fw21 stubs (#3080)

Adds fully functional overlay display.
- Enable Overlay Applet via "View" -> "Enable Overlay Display Applet"
- Open the overlay by pressing the home button for over 1s
- Can adjust volume
- Can toggle airplane mode (if on WiFi, maybe if overlay is enabled pretend to be on WiFi?)
- Future TODO(?): Adjust Brightness implementation for host system
- Inputs are properly registered. e.g. if overlay open, application does not register inputs.

You can control volume and airplane mode outside of the emulator window

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3080
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: crueter <crueter@eden-emu.dev>
Co-authored-by: Maufeat <sahyno1996@gmail.com>
Co-committed-by: Maufeat <sahyno1996@gmail.com>

src/core/hle/service/npns/npns.cpp

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -150,16 +153,17 @@ private:
 
 class INpnsUser final : public ServiceFramework<INpnsUser> {
 public:
-    explicit INpnsUser(Core::System& system_) : ServiceFramework{system_, "npns:u"} {
+    explicit INpnsUser(Core::System& system_)
+        : ServiceFramework{system_, "npns:u"}, service_context{system, "npns:u"} {
         // clang-format off
         static const FunctionInfo functions[] = {
             {1, nullptr, "ListenAll"},
             {2, nullptr, "ListenTo"},
             {3, nullptr, "Receive"},
             {4, nullptr, "ReceiveRaw"},
-            {5, nullptr, "GetReceiveEvent"},
+            {5, C<&INpnsUser::GetReceiveEvent>, "GetReceiveEvent"},
             {7, nullptr, "GetStateChangeEvent"},
-            {8, nullptr, "ListenToByName"}, // 18.0.0+
+            {8, C<&INpnsUser::ListenToByName>, "ListenToByName"}, // 18.0.0+
             {21, nullptr, "CreateToken"},
             {23, nullptr, "DestroyToken"},
             {25, nullptr, "QueryIsTokenValid"},
@@ -178,7 +182,33 @@ public:
         // clang-format on
 
         RegisterHandlers(functions);
+
+        get_receive_event = service_context.CreateEvent("npns:u:GetReceiveEvent");
     }
+
+    ~INpnsUser() override {
+        service_context.CloseEvent(get_receive_event);
+    }
+
+private:
+    Result ListenToByName(InBuffer<BufferAttr_HipcMapAlias> name_buffer) {
+        const std::string name(reinterpret_cast<const char*>(name_buffer.data()), name_buffer.size());
+        LOG_DEBUG(Service_NPNS, "called, name={}", name);
+
+        // Store the name for future use if needed
+        // For now, just acknowledge the registration
+        R_SUCCEED();
+    }
+
+    Result GetReceiveEvent(OutCopyHandle<Kernel::KReadableEvent> out_event) {
+        LOG_DEBUG(Service_NPNS, "called");
+
+        *out_event = &get_receive_event->GetReadableEvent();
+        R_SUCCEED();
+    }
+
+    KernelHelpers::ServiceContext service_context;
+    Kernel::KEvent* get_receive_event;
 };
 
 void LoopProcess(Core::System& system) {