Uninstalling chaiNNer does not remove files in HOME on Linux

[RunDevelopment]

Description
Uninstalling chaiNNer on Linux leaves behind files in ~/.config/chaiNNer/ (which contains our integrated python) and ~/.cache/chainner_pip/ (which is basically the package download cache).

Those directories should be removed (mostly) when uninstalling chaiNNer. The only thing that should be left are ~/.config/chaiNNer/settings.json and ~/.config/chaiNNer/logs/. Settings are good to keep for re-installs and logs are important to diagnose issues.

The main task here will be to figure out how to run our code during package uninstallation or how to make the (un)installer remove those files for us.

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Originally reported by @ipeevski here.

On linux, the directory is $HOME/.config/chaiNNer It's north of 5Gb after uninstall ...

Another directory that is left over is $HOME/.cache/chainner_pip