IDF built app download config may change with some modification.
save the download configs for built APP in build stage.
then we can use the correct download config in test stage.
rename nvs host test folder, modify .gitlab-ci.yml
remove unit-test-app build
re-format unit test files
remove extra newlines in project.mk
some refactoring for unit test part in project.mk
add build files of unit-test-app in gitignore
add README.md for unit test app
correct headings in README.md
remove files and make minor tweaks in unit test app
update .gitlab-ci.yml to use unit test app
delete unused lines in component_wrapper.mk
delete periph_i2s.h and lcd test
add text floating point in components/esp32/test/Kconfig
correct idf test build paths in .gitlab-ci.yml
