Incorrect path separators on Linux

[TacoConKvass]

What's the bug

On Linux incorrect path separators are used in the loader, causing files to generate at the game's root with their absolute paths with / replaced with \\ as their name

Steps to reproduce

NA

Proposed fix

Replace all path concatenation with Path.Combine calls. Should have been like that since the beginning, but my laziness won

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Thanks to @darrel1699 for the report in the CDG Discord server