Getting ISIS test data with rclone

[oleg-alexandrov]

The current doc for how to get the ISIS test data with rclone at

https://github.com/DOI-USGS/ISIS3?tab=readme-ov-file#how-to-download-the-isis-test-data-with-rclone

is not easy to use. The user has to go through very many configuration steps, with some of them having 25 and even 40 options to choose from. Enough to make one's eyes roll, when it comes to choosing sites, providers, regions, storage classes, etc.

Once the configuration is over, nothing really happens, and no info is given about where the rclone config file went, as it is not saved in the current directory.

The relevant rclone file for the test data should be saved as part of the repo, as done anyway for ISIS data itself, and the user should be told how to pass that config file to rclone.

[oleg-alexandrov]

Ideally one would run a command such as:

downloadIsisData isistestdata