Decide on where and how to store test data

[lbergelson]

No description provided.

[magicDGS]

Some options:

• data folder in root: allows to share between different modules, but it is not packaged in the test files
• src/test/resources for each module: difficult to share, but can be packaged in the test jars (and thus, self-contained test jars)
• Some files can also live in a test-helper package to be distributed and used by downstream applications for testing (requires a separate test-helper module/artifact)
• Other options, like an integration-test sources directory (e.g., https://www.petrikainulainen.net/programming/gradle/getting-started-with-gradle-integration-testing/)

[magicDGS]

Also, are we going to check big files with git-lfs? Or better to store them somewhere else and download on testing with big files? Or a combination of both?