Add user config git.preferRemotes to OpenInBrowser on specified remotes

[phanen]

• PR Description

When I clone a new repo, after gh repo fork, origin will be renamed to upstream.
In this case, I hope OpenInBrowser to try upstream first.

With this git.preferRemotes option, this behavior can be implemented by:

git:
  preferRemotes:
  - upstream
  - origin

• Please check if the PR fulfills these requirements

• Cheatsheets are up-to-date (run go generate ./...)
• Code has been formatted (see here)
• Tests have been added/updated (see here for the integration test guide)
• Text is internationalised (see here)
• If a new UserConfig entry was added, make sure it can be hot-reloaded (see here)
• Docs have been updated if necessary
• You've read through your own file changes for silly mistakes etc