bext: fix "Open on Sourcegraph" button for files with symbols in the filePath
Created by: erzhtor
Closes https://github.com/sourcegraph/sourcegraph/issues/33310.
Test plan
sg run bext- Open https://gitlab.com/pedropombeiro/dotfiles/-/blob/master/.shellrc/zshrc.d/functions/gdk.sh%23%23class.Work#L55-L117
- Check that "Open on Sourcegraph" button on a file toolbar correctly opens file on Sourcegraph
- Check that it works for other files without special symbols in filePath