Special Support for `.exe` and `.sys` in `maps64`/`maps32`

[sylv256]

Currently, libscemu tries to find dependencies in maps64/maps32 by adding .dll to the end. However, this does not work when the file is a .exe or .sys (for example, when emulating a .sys). The workaround right now is to add .dll to the end of these files so that they can be resolved.