When packaged into pyz (zip file), resources are not directly available on filesystem and therefore we can't always rely on os.listdir() and open() to enumerate and read them.
We are going to use importlib.resources() to solve this problem, except python 3.8 and older, where there is no function (files()) available to enumerate resources. For legacy (3.8 actually becomes EOL in October 2024) python versions we are going to use os.listdir() as a fallback.
Close#3017
