Don't auto-import 'Proton' versions from Steam

[IronVeil]

Is your feature request related to a problem? Please describe.
As seen below, the Steam auto-import feature decides to import 'Proton' versions.

These cannot be ran, and always throw an error when opened:

Describe the solution you'd like
The Steam auto-import feature should automatically ignore any libraries, such as Proton or the Steam Linux Runtime.

[kramo]

There is no proper way of filtering these out thanks to the Steam API. I could do it and I did it in the past but it broke other things.

[kramo]

I thought about it a bit, but there is no non-hacky way to do this. Blame Valve 🤷