Add build_unit_test.sh to do find_apps and build_apps to unit_tests

modify unit-test-apps config files, use CONFIG_IDF_TARGET to set target.
if not set, then treat them as supported both targets.

tools/ci/executable-list.txt

@@ -36,6 +36,7 @@ tools/ci/apply_bot_filter.py
 tools/ci/build_examples.sh
 tools/ci/build_examples_cmake.sh
 tools/ci/build_test_apps.sh
+tools/ci/build_unit_test.sh
 tools/ci/check-executable.sh
 tools/ci/check-line-endings.sh
 tools/ci/check_build_warnings.py
@@ -43,7 +44,6 @@ tools/ci/check_deprecated_kconfigs.py
 tools/ci/check_examples_cmake_make.sh
 tools/ci/check_examples_rom_header.sh
 tools/ci/check_idf_version.sh
-tools/ci/check_public_headers.sh
 tools/ci/check_ut_cmake_make.sh
 tools/ci/checkout_project_ref.py
 tools/ci/deploy_docs.py