Create an empty versions.txt if it doesn't exist in repository-path

[JoeWang1127]

In the hermetic library generation process, we require a versions.txt file exists in repository-path; otherwise raise FileNotFoundError in

sdk-platform-java/hermetic_build/library_generation/utils/utilities.py

Line 164 in 7d6d66a

raise FileNotFoundError(f"{versions_file} is not found.")

We didn't check the content of this file and the post processor can add versions for new client, therefore we should create an empty file if not exist, rather than raise an exception.

The generated library will have a 0.0.1-SNAPSHOT version.