Extract UsbCommand_SetTestLed() into its own file.

right/src/usb_commands/usb_command_set_test_led.c

@@ -0,0 +1,11 @@
+#include "usb_commands/usb_command_set_test_led.h"
+#include "usb_protocol_handler.h"
+#include "peripherals/test_led.h"
+#include "slave_drivers/uhk_module_driver.h"
+
+void UsbCommand_SetTestLed(void)
+{
+    uint8_t ledState = GenericHidInBuffer[1];
+    TEST_LED_SET(ledState);
+    UhkModuleStates[UhkModuleDriverId_LeftKeyboardHalf].sourceVars.isTestLedOn = ledState;
+}

right/src/usb_commands/usb_command_set_test_led.h

@@ -0,0 +1,8 @@
+#ifndef __USB_COMMAND_SET_TEST_LED_H__
+#define __USB_COMMAND_SET_TEST_LED_H__
+
+// Functions:
+
+    void UsbCommand_SetTestLed(void);
+
+#endif