Fix use of DLLOpenCFile with std::filesystem::path making multiplayer crash

[Lgt2x]

Pull Request Type

• [ ] GitHub Workflow changes
• [ ] Documentation or Wiki changes
• [ ] Build and Dependency changes
• [x] Runtime changes
  • [ ] Render changes
  • [ ] Audio changes
  • [ ] Input changes
  • [x] Network changes
  • [ ] Other changes

Description

Conversion from char * to const std::filesystem::path & did not go as #486 expected, making the game crash when starting multiplayer, because filename provided to cfopen was null. This fixes the issue by doing explicit conversions

Related Issues

Fixup #486