Block Internet

[Block Internet](https://github.com/frostworx/steamtinkerlaunch/wiki/Block Internet)

When enabling BLOCKINTERNET per game in Game Menu, stl tries to block the internet access for the game by prepending unshare -n -r to the game launch

You might want to read this if you have problems with the -r parameter

(when testing unshare-net via bwrap, the test game could not find its data-files, so is hardcoded for now - feel free to submit a PR)

Of course, not every game works without internet access.

The option can also be enabled by putting the game into the BlockInternet Steam Category