Add Firmware 20.0.0-21.0.0 IPC support and stubs

This commit implements comprehensive firmware 20.0.0 through 21.0.0
support for Citron, including:

- Updated firmware version constants to 21.0.0 in api_version.h
- Updated HID service firmware version string to 21.0.0
- Added IPC command stubs for firmware 20.0.0+ in:
  * ISystemSettingsServer (commands 263, 264, 282, 283, 289, 300, 301, 306, 307)
  * IFirmwareDebugSettingsServer (command 24)
  * IApplicationFunctions (command 330)
  * IOlscServiceForSystemService (command 914)
  * IRemoteStorageController (commands 28, 901)
  * IService (migration) (commands 2250, 2260)
  * IAudioController (command 10200)

- Created new service interfaces with proper stubs:
  * IContinuousRecorder (grcsrv) - command 5 [20.2.0+] with 0x20-byte input
  * IDownloadContext (news) - command 4 [20.0.0+]
  * INotifyService (pdm:ntfy) - commands 100, 101 [20.0.0+] returning outinterfaces

- Added all new source files to CMakeLists.txt build system
- Fixed logging tag usage (Service_Migration instead of Service_MIG)
- Added required CMIF serialization headers for proper template instantiation

All stubs return success explicitly, eliminating the need for auto-stubbing.
All implementations follow Switchbrew documentation as closely as possible.

Based on Switchbrew documentation:
- https://switchbrew.org/wiki/21.0.0
- https://switchbrew.org/wiki/20.5.0
- https://switchbrew.org/wiki/20.4.0
- https://switchbrew.org/wiki/20.3.0
- https://switchbrew.org/wiki/20.2.0
- https://switchbrew.org/wiki/20.1.5
- https://switchbrew.org/wiki/20.1.1
- https://switchbrew.org/wiki/20.1.0
- https://switchbrew.org/wiki/20.0.1
- https://switchbrew.org/wiki/20.0.0

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/core/hle/service/set/firmware_debug_settings_server.cpp

@@ -1,6 +1,9 @@
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include "common/logging/log.h"
+#include "core/hle/service/cmif_serialization.h"
 #include "core/hle/service/set/firmware_debug_settings_server.h"
 
 namespace Service::Set {
@@ -18,6 +21,7 @@ IFirmwareDebugSettingsServer::IFirmwareDebugSettingsServer(Core::System& system_
         {21, nullptr, "SetAllowedSslHosts"},
         {22, nullptr, "SetHostFsMountPoint"},
         {23, nullptr, "SetMemoryUsageRateFlag"},
+        {24, D<&IFirmwareDebugSettingsServer::Unknown24>, "Unknown24"}, // [20.0.0+]
     };
     // clang-format on
 
@@ -26,4 +30,9 @@ IFirmwareDebugSettingsServer::IFirmwareDebugSettingsServer(Core::System& system_
 
 IFirmwareDebugSettingsServer::~IFirmwareDebugSettingsServer() = default;
 
+Result IFirmwareDebugSettingsServer::Unknown24() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown24 [20.0.0+]");
+    R_SUCCEED();
+}
+
 } // namespace Service::Set

src/core/hle/service/set/firmware_debug_settings_server.h

@@ -15,6 +15,9 @@ class IFirmwareDebugSettingsServer final : public ServiceFramework<IFirmwareDebu
 public:
     explicit IFirmwareDebugSettingsServer(Core::System& system_);
     ~IFirmwareDebugSettingsServer() override;
+
+private:
+    Result Unknown24(); // [20.0.0+]
 };
 
 } // namespace Service::Set

src/core/hle/service/set/system_settings_server.cpp

@@ -301,6 +301,15 @@ ISystemSettingsServer::ISystemSettingsServer(Core::System& system_)
         {208, nullptr, "SetHearingProtectionSafeguardFlag"},
         {209, nullptr, "GetHearingProtectionSafeguardRemainingTime"},
         {210, nullptr, "SetHearingProtectionSafeguardRemainingTime"},
+        {263, C<&ISystemSettingsServer::Unknown263>, "Unknown263"}, // [20.0.0+]
+        {264, C<&ISystemSettingsServer::Unknown264>, "Unknown264"}, // [20.0.0+]
+        {282, C<&ISystemSettingsServer::Unknown282>, "Unknown282"}, // [20.0.0+]
+        {283, C<&ISystemSettingsServer::Unknown283>, "Unknown283"}, // [20.0.0+]
+        {289, C<&ISystemSettingsServer::Unknown289>, "Unknown289"}, // [20.0.0+]
+        {300, C<&ISystemSettingsServer::Unknown300>, "Unknown300"}, // [20.0.0+]
+        {301, C<&ISystemSettingsServer::Unknown301>, "Unknown301"}, // [20.0.0+]
+        {306, C<&ISystemSettingsServer::Unknown306>, "Unknown306"}, // [20.0.0+]
+        {307, C<&ISystemSettingsServer::Unknown307>, "Unknown307"}, // [20.0.0+]
     };
     // clang-format on
 
@@ -1389,4 +1398,49 @@ Result ISystemSettingsServer::GetSettingsItemValueImpl(std::span<u8> out_value,
     R_SUCCEED();
 }
 
+Result ISystemSettingsServer::Unknown263() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown263 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown264() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown264 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown282() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown282 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown283() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown283 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown289() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown289 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown300() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown300 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown301() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown301 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown306() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown306 [20.0.0+]");
+    R_SUCCEED();
+}
+
+Result ISystemSettingsServer::Unknown307() {
+    LOG_WARNING(Service_SET, "(STUBBED) called Unknown307 [20.0.0+]");
+    R_SUCCEED();
+}
+
 } // namespace Service::Set

src/core/hle/service/set/system_settings_server.h

@@ -155,6 +155,15 @@ public:
     Result GetFieldTestingFlag(Out<bool> out_field_testing_flag);
     Result GetPanelCrcMode(Out<s32> out_panel_crc_mode);
     Result SetPanelCrcMode(s32 panel_crc_mode);
+    Result Unknown263(); // [20.0.0+]
+    Result Unknown264(); // [20.0.0+]
+    Result Unknown282(); // [20.0.0+]
+    Result Unknown283(); // [20.0.0+]
+    Result Unknown289(); // [20.0.0+]
+    Result Unknown300(); // [20.0.0+]
+    Result Unknown301(); // [20.0.0+]
+    Result Unknown306(); // [20.0.0+]
+    Result Unknown307(); // [20.0.0+]
 
 private:
     bool LoadSettingsFile(std::filesystem::path& path, auto&& default_func);