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.

.gitignore

@@ -40,6 +40,10 @@ tools/unit-test-app/sdkconfig.old
 tools/unit-test-app/build
 tools/unit-test-app/builds
 tools/unit-test-app/output
+tools/unit-test-app/test_configs
+
+# Unit Test CMake compile log folder
+log_ut_cmake
 
 # IDF monitor test
 tools/test_idf_monitor/outputs