create binary symlinks with relative location

[UiP9AV6Y]

since the installed binary as well as the symlink reside in the same directory, relative paths should be safe to use without having to worry about crossing filesystem boundaries.

closes #158

[bwplotka]

Nice! I like this change but it would be good to have a green CI on this, let's rebase once we fix main tests: https://github.com/bwplotka/bingo/issues/162

We could also add dedicated unit test so we don't break this invariant of portability of symlinks

[bwplotka]

Can you also rebase? We fixed build.