ci(tools): Move misspelled KConfig test to dedicated kconfig_test_app

Separate the misspelled KConfig.projbuild test case into its own test app
so it doesn't interfere with the general-purpose build_test_app. The test
now uses a pytest marker to select kconfig_test_app as the source.

tools/test_build_system/kconfig_test_app/CMakeLists.txt

@@ -0,0 +1,9 @@
+cmake_minimum_required(VERSION 3.22)
+
+# placeholder_before_include_project_cmake
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+
+# placeholder_after_include_project_cmake
+
+project(kconfig_test_app)

tools/test_build_system/kconfig_test_app/README.md

@@ -0,0 +1,3 @@
+Information about this test app can be found [here](../README.md#application-under-test).
+
+This is a 1:1 copy of build_test_app, but with a malformed KConfig.projbuild file.

tools/test_build_system/kconfig_test_app/main/CMakeLists.txt

@@ -0,0 +1,5 @@
+# placeholder_before_idf_component_register
+
+idf_component_register(SRCS "kconfig_test_app.c"
+                       # placeholder_inside_idf_component_register
+)

tools/test_build_system/kconfig_test_app/main/KConfig.projbuild

@@ -0,0 +1,4 @@
+# Misspelled Kconfig file checks whether it is picked up by the build system
+config FROM_MISSPELLED_KCONFIG
+    bool "From misspelled Kconfig"
+    default y

tools/test_build_system/kconfig_test_app/main/kconfig_test_app.c

@@ -0,0 +1,12 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <stdio.h>
+// placeholder_before_main
+
+void app_main(void)
+{
+    // placeholder_inside_main
+}