Add GitHub user/repo generator

[clo4]

I will work on this.

Using username/repo is a common shorthand for GitHub repos, used at minimum by:

• degit
• gh
• brew tap

And I frequently find myself using this pattern for personal CLIs (eg. vim package manager, git clone for my own directory structure, etc)

What would be necessary:

• Sort by stars
• Map user suggestion (user: Fig.Suggestion) => Fig.Suggestion
• Map repo suggestion (repo: Fig.Suggestion) => Fig.Suggestion
• Disable user suggestions
• Disable repo suggestions
• Conditionally disable, default would be lastToken.slice(lastToken.indexOf("/")).match(githubUsernameRegex)

import { github } from "@fig/generators";

// ...

{
  args: {
    debounce: true,
    generators: github({
      // Could be `suggestUsers?: boolean | ((user: Fig.Suggestion) => Fig.Suggestion)
      suggestUsers: false,
      suggestRepos: (repo) => ({ ...repo, icon: "📦" }),
      includeForks: false,
      includeTemplates: false,
    }),
  }
}