Add integration tests

[remyroy]

It would be nice to have integration tests that test larger sections of the codebase and have them run in the CI workflows.

Tests that we are not currently always running are in test_binary_btec_script.py, test_binary_deposit_script.py, test_btec_script.py and test_deposit_script.py. We could reuse those tests.

[remyroy]

It seems like we already have some with the various tests in tests/test_cli. We might be able to expand those tests.