Write some simple support to run jest in ansi-term/tmux session for the specific project

[Fuco1]

• [ ] have a tmux session started for the "project"
• [ ] have a way to visit that session in some popup buffer
• [ ] (make tmux optional?)
• [ ] have some cleanup
• [ ] pop-to-jest on error

Maybe we don't have to use tmux for this and just launch multiple ansi-term buffers instead. Either could work I think.