chore: add GUT test framework

addons/gut/scratch/file_dir_access.gd

@@ -0,0 +1,50 @@
+extends SceneTree
+
+func fa_print_open_for_read_result(path):
+    var file = FileAccess.open(path, FileAccess.READ)
+    var result = FileAccess.get_open_error()
+    print('Open(read) ', path)
+    print('var file = ', file)
+    if(result == OK):
+        print(' is OK')
+    else:
+        print('  Error code ', result)
+
+    return result
+
+func fa_print_open_for_write_result(path):
+    var file = FileAccess.open(path, FileAccess.WRITE)
+    var result = FileAccess.get_open_error()
+    print('Open(write) ', path)
+    print('var file = ', file)
+    if(result == OK):
+        print(' is OK')
+    else:
+        print('  Error code ', result)
+
+    return result
+
+func da_print_open_result(path):
+    var dir = DirAccess.open(path)
+    var result = DirAccess.get_open_error()
+
+    print('Open Dir ', path)
+    print('var dir = ', dir)
+    if(result == OK):
+        print(' is OK')
+    else:
+        print('  Error code ', result)
+
+    return result
+
+func _init():
+    fa_print_open_for_read_result('res://addons/gut/gut.gd')
+    fa_print_open_for_read_result('res://file_dne.biz')
+
+    fa_print_open_for_write_result('user://foo.txt')
+    fa_print_open_for_write_result('bar://foo.txt')
+
+    da_print_open_result('res://addons')
+    da_print_open_result('res://dne')
+
+    quit()