Support for private GitHub Enterprise installations

The base GitHub API URLs are hard-coded inside the GithubAPIv3Config class:

case class GithubAPIv3Config(
    baseUrl: String = "https://api.github.com/",
    authorizeUrl: String =
      "https://github.com/login/oauth/authorize?client_id=%s&redirect_uri=%s&scope=%s&state=%s",
    accessTokenUrl: String = "https://github.com/login/oauth/access_token"
)

which makes impossible to leverage github4s in those companies which use their private GitHub installations and obviously different base API URLs.

Currently it seems there’s no way to override these URLs.

[BenFradet]

yes I think it needs renaming, maybe something like:

final case class GithubConfig(
  baseUrl: String = "https://api.github.com/",
  authorizeUrl: String = "https://github.com/login/oauth/authorize?client_id=%s&redirect_uri=%s&scope=%s&state=%s",
  accessTokenUrl: String = "https://github.com/login/oauth/access_token"
)

object GithubConfig {  
  implicit val default: GithubConfig = GithubConfig()
}

and then have:

class Github[F[_]: Sync](
    client: Client[F],
    accessToken: Option[String]
)(implicit ghConfig: GithubConfig)

👍

[satorg]

@BenFradet, I submitted a PR #384, could you take a look please?