bootctl: Initial experimentation

This provides a basic prototype for boot control.

Some documentation is in boot/bootctl/README.rst

test/boot/bootctl/bootctl_common.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Common definitions for bootctl tests
+ *
+ * Copyright 2025 Canonical Ltd
+ * Written by Simon Glass <simon.glass@canonical.com>
+ */
+
+#ifndef __bootctl_common_h
+#define __bootctl_common_h
+
+#define BOOTCTL_TEST(_name, _flags)	UNIT_TEST(_name, _flags, bootctl)
+
+#endif