Add a portable version of the package

[scowalt]

From #74

Ideally, the package shouldn't use the installer at all and should be based on the zip archive. The only difference is the lack of the config file and thus the missing --ffmpeg-ffmpeg CLI arg by default.

The scoop package does the correct thing and builds a wrapper executable which sets the --ffmpeg-ffmpeg CLI argument to the path of the bundled ffmpeg executable which the installer would do otherwise automatically.