Port currently unsupported commands to Linux

[reibitto]

Some of these might be more involved considering different flavors of Linux might need different solutions. If so, it might also be a good idea to create a LinuxFlavor ADT similar to how OS.scala is done.

• FindFileCommand
• FindInFileCommand
• LockCommand
• ProcessIdCommand
• TimerCommand
• ToggleDesktopIconsCommand
• ToggleHiddenFilesCommand