Write initial PR description using editor while respecting the pull_request_template.md

**Topic**
Creating PR using editor (vim/nvim) while respecting the pull_requuest_template.md or yml file etc

**Your thoughts**
I think what we have here is a genius piece of work while every effort has been made to ensure we have a great experience; im getting lazy opening PRs.

So i thought layzgit could get `lazier`

Im thinking we should have an option of opening a PR through our editor (i'll personally prefer opening a PR and filling information up in vim/nvim) instead of the web UI.

like; we can open the editor when we `e` into a file; surely we can do the same for opening a PR. what do you guys think?