Join commit message lines on PR creation

[jaminthorns]

Both on GitHub and this extension, there's functionality where if you're creating a PR from a single commit, it will use the commit subject as the PR title and the commit message body as the PR description. In Git commits, it's conventional to wrap commit messages at 72 characters (VS Code even has a default ruler for this) for command-line tooling.

In GitHub, there's some smartness to unwrap those lines when translating the commit message body into the PR description. It would be nice if this extension had that functionality as well.

[justingrant]

I just ran into this problem and it's severe enough that I don't really want to use the extension to create PRs, because manually unwrapping lines for long commit messages is fairly labor intensive.

It'd be create to match the behavior of the GH web app where line breaks are unwrapped when copying the commit message.