Describe the feature or problem you’d like to solve

I used gh pr create (surprised that it defaulted to open my PR from a fork into the upstream repo - it was awesome🤩) and when I went to edit the PR body, it defaulted to nano but I'd prefer it to use vim.

Proposed solution

1. When a user first install gh prompt them to choose a default editor:

• nano
• vim

2. Let a user specify editor

gh set-editor vim

How will it benefit CLI and its users?

• it will support nano and vim users ❤️

Additional context

N/A