Remove CrossOver support on Linux

[CommandMC]

This wasn't working, it made the code unnecessarily complex, and I don't think anyone ever used it.

The usual settings issues are present (namely, if someone used CX and doesn't change the version to something else, the old settings stay and things will go wrong). Guess this'll get better after the settings refactor

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Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[flavioislima]

LGTM 👍🏽