cs: implement TakeScreenShot command

libraries/libstratosphere/source/cs/cs_command_impl.hpp

@@ -18,6 +18,16 @@
 
 namespace ams::cs {
 
+    struct CommandDataTakeScreenShot {
+        vi::LayerStack layer_stack;
+        std::function<void (s32, s32, s32)> send_header;
+        std::function<void (u8 *, size_t)> send_data;
+        u8 *buffer;
+        size_t buffer_size;
+    };
+
     Result DoGetFirmwareVersionCommand(settings::system::FirmwareVersion *out);
 
+    Result DoTakeScreenShotCommand(const CommandDataTakeScreenShot &params);
+
 }