feat(bootloader): add the possibility to specify extra components directories

examples/custom_bootloader/bootloader_extra_dir/main/CMakeLists.txt

@@ -0,0 +1,2 @@
+idf_component_register(SRCS "bootloader_hooks_example_main.c"
+                    INCLUDE_DIRS ".")

examples/custom_bootloader/bootloader_extra_dir/main/bootloader_hooks_example_main.c

@@ -0,0 +1,11 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
+#include <stdio.h>
+
+void app_main(void)
+{
+    printf("User application is loaded and running.\n");
+}