RpfFile:
- Limit RPF entry names to 256 characters because long names can cause the RPFExplorer to freeze when opening its directory.
- Skip RPFs with paths longer that 5000 characters, which are probably an attempt to make CW run out-of-memory.
ExploreForm:
- Use `Path.GetExtension` directly instead of `FileInfo` to prevent `PathTooLongException`s.
- Check for invalid characters in file names to prevent `ArgumentException`s.
