bootloader: Kconfig files in bootloader_components is now part of menuconfig

It is now possible to configure the options (Kconfig) of bootloader components
directly from the menuconfig

examples/custom_bootloader/bootloader_override/bootloader_components/main/Kconfig

@@ -0,0 +1,8 @@
+menu "Bootloader welcome message"
+
+    config EXAMPLE_BOOTLOADER_WELCOME_MESSAGE
+        string "Bootloader welcome message"
+        default "Custom bootloader message defined in the KConfig file."
+        help
+            Message to print by the custom bootloader when booting up.
+endmenu

examples/custom_bootloader/bootloader_override/bootloader_components/main/bootloader_start.c

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 #include <stdbool.h>
+#include "sdkconfig.h"
 #include "esp_log.h"
 #include "bootloader_init.h"
 #include "bootloader_utility.h"
@@ -41,7 +42,7 @@ void __attribute__((noreturn)) call_start_cpu0(void)
     }
 
     // 2.1 Print a custom message!
-    esp_rom_printf("[%s] Custom bootloader has been initialized correctly.\n", TAG);
+    esp_rom_printf("[%s] %s\n", TAG, CONFIG_EXAMPLE_BOOTLOADER_WELCOME_MESSAGE);
 
     // 3. Load the app image for booting
     bootloader_utility_load_boot_image(&bs, boot_index);

examples/custom_bootloader/bootloader_override/example_test.py

@@ -10,7 +10,10 @@ def test_custom_bootloader_impl_example(env, _):  # type: ignore
     dut.start_app()
 
     # Expect to read a message from the custom bootloader
-    dut.expect('Custom bootloader has been initialized correctly.')
+    # This message is defined in the Kconfig file, retrieve it while deleting
+    # leading and trailing quotes (")
+    welcome_message = dut.app.get_sdkconfig()['CONFIG_EXAMPLE_BOOTLOADER_WELCOME_MESSAGE'].strip("\"")
+    dut.expect(welcome_message)
 
     # Expect to read a message from the user application
     dut.expect('Application started!')