MMU-239 Implement unit test for ejecting slots 0 to 4 (and FINDA flickering recovery)

[gudnimg]

This just a basic test, I want to add some more checks in between states later

TODO:

• [x] Add unit test for FINDA_FLICKERS error code
• [x] Add unit test to test selector parking position for all ejected slots.

[gudnimg]

I think this PR is now ready for review. It's certainly better than nothing :)