feat: allow for relative parts when specifying a path to a file on the CLI

[therapon]

Summary While using the CLI (to load data for example) we are required to pass the location of a file. It seems like the location has to be a full path else the load fails and the error message reports Internal Error

For example

./kaskada-cli load \
     --table Purchase \
     --file-path file:///purchase.parquet

See

• https://github.com/kaskada-ai/kaskada/issues/202#issuecomment-1496483413
• #208

Describe the solution you'd like

• [ ] It would be nice to have a working example that allows passing in local paths instead of full paths

• [x] The error message when the file provided in the path argument is missing or otherwise unavailable should be more informative, e.g., "Cannot find/open file " or similar. There is already an issue on the case where the file does not exist #98

[bjchambers]

For the CLI, I would expect to say something like ./kaskada-cli load --table Purchase --file-path ./purchase.parquet and have the CLI take care of making that work. That would be more consistent with how basically every CLI works with local files, right?