[Feature Request]: Unit Test consider a different file format

### What would you like to happen?

Unit tests currently use CSV files which are unfriendly to Blobs and other text containing commas carriage returns, etc.

Please enable the use of a different file format e.g. avro as a dataset source so that we have a more flexible unit test universe.

### Issue Priority

Priority: 3

### Issue Component

Component: Hop Gui

Start in Hop Gui's unit-test dataset source handling and trace how CSV files are loaded. Compare the current behavior with the requested Avro or other alternate format, especially datasets containing blobs, commas, and carriage returns. Done means unit tests can use a more flexible file format as a dataset source, with coverage for those values.

Written by the indexing model from the issue text.