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/CMakeLists.txt

@@ -581,6 +581,8 @@ add_library(core STATIC
     hle/service/bcat/delivery_cache_storage_service.h
     hle/service/bcat/delivery_task_suspension_service.cpp
     hle/service/bcat/delivery_task_suspension_service.h
+    hle/service/bcat/news/download_context.cpp
+    hle/service/bcat/news/download_context.h
     hle/service/bcat/news/newly_arrived_event_holder.cpp
     hle/service/bcat/news/newly_arrived_event_holder.h
     hle/service/bcat/news/news_data_service.cpp
@@ -721,6 +723,8 @@ add_library(core STATIC
     hle/service/glue/time/time_zone_binary.h
     hle/service/glue/time/worker.cpp
     hle/service/glue/time/worker.h
+    hle/service/grc/continuous_recorder.cpp
+    hle/service/grc/continuous_recorder.h
     hle/service/grc/grc.cpp
     hle/service/grc/grc.h
     hle/service/hid/active_vibration_device_list.cpp
@@ -853,6 +857,8 @@ add_library(core STATIC
     hle/service/ns/language.h
     hle/service/ns/ns.cpp
     hle/service/ns/ns.h
+    hle/service/ns/notify_service.cpp
+    hle/service/ns/notify_service.h
     hle/service/ns/ns_results.h
     hle/service/ns/ns_types.h
     hle/service/ns/platform_service_manager.cpp