Stack navigation

[vineus]

Hey there!

Thank you so much for adding native stack support to github 🙇‍♂️

Stack navigation is currently cumbersome, would to have:

1. gh stack trunk (move to trunk)
2. interactive navigation with gh stack checkout to select a specific branch from a stack

[skarim]

We added a gh stack switch command in #51 that opens up an interactive navigation to checkout a specific branch in a stack.

I like the idea of a command to move to the trunk branch, will explore some ideas here.