`gh browse` command should automatically run `gh repo set-default` if not yet configured

### Describe the feature or problem you’d like to solve

When I clone a new fork repo (`git clone `), and add the upstream remote locally to have both (my fork and original) repo as remotes configured (`git remote add upstream `), and I run `gh browse` for the first time, it always bothers me that I have to manually copy and paste the suggested `gh repo set-default` command, instead of `gh browse` just auto-executing the command for me, so I can select the default repo and it opens fluently.

### Proposed solution

When I run `gh browse` I would expect that it automatically asks the CLI user to select the configuration for the default remote to open.

- [x] I'm willing to submit a PR which implements this feature request.