Test interaction with devices in toolbxes

**Is your feature request related to a problem? Please describe.**
Toolbx has a small suite of tests that currently mainly test the CLI interface and it's immediate effects. There is no suite that tests the toolbx environment, though. Part of such a test suite would be the testing of devices (e.g., USB sticks).

**Describe the solution you'd like**
A test suite for testing manipulation of devices in a toolbx

**Additional context**
https://github.com/martinpitt/umockdev is a tool that might be very useful for this particular test suite.