Add a license header

Add a license header to glcdfont.c

.vscode/settings.json

@@ -30,5 +30,6 @@
     },
     "clangd.arguments": [
         "--header-insertion=never"
-    ]
+    ],
+    "cmake.sourceDirectory": "C:/qmk_firmware/lib/googletest"
 }

keyboards/gkeyboard/greatpad/lib/glcdfont.c

@@ -1,3 +1,6 @@
+// Copyright 2023 gkeyboard (@gkeyboard)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
 // This is the 'classic' fixed-space bitmap font for Adafruit_GFX since 1.0.
 // See gfxfont.h for newer custom bitmap font info.