We've got a few ways to get a PR object right now, and they are all slightly different and require a lot of boilerplate code. This creates a consistent interface for that lookup. It might sound familiar because I tried it before in #926 but this time it will work!

The plan

This is going to be a two step process.

1. Get the commands using the same pr lookup interface prFromArgs. This will look at the commands args to find the PR via a number, url, branch name or whatever the current branch of the existing git repo is. This is what I solved in this PR.

2. Add an argument to prFromArgs that lets you pick what type of PR response you want back. This was mislav's magical reflection idea that we got working in https://github.com/cli/cli/compare/pr-get-query

Things I considered while writing this.

• I pass the args string to prFromArgs because if passed the string itself like args[0] we'd get a panic when there are no args or we'd need a conditional before each call. This seemed annoying and passing the args array worked out well enough.
• This does create an extra api in some commands because previously we only needed the PR number. But this is not common and I feel like it gives us the extra benefit of verifying that the PR exists.