Feature Request: remote repo selector

## Is your feature request related to a problem? Please describe.

Apparently this extension assumes the GitHub repository to use is the `git remote` named `origin`. I use a fork-based development workflow, and I haven't been using `origin` as a remote name at all, as [it's arguably unclear](https://stackoverflow.com/a/38986590). (Does it refer to my fork, or the upstream/canonical repo?) Additionally, even if the meaning of `origin` is clear, this limitation doesn't allow users to choose between multiple remotes.

## Describe the solution you'd like

Add a pulldown selector somewhere in the GITHUB ACTIONS sidepanels, to allow choosing. Save the setting for each workspace.

## Additional context

(None.)

Comienza siguiendo cómo la extensión descubre el repositorio actual de GitHub y cómo se ensamblan los paneles laterales de GITHUB ACTIONS. Inspecciona primero el flujo de configuración del workspace y la gestión de los remotes; se considera terminado cuando un selector del panel lateral puede elegir entre los remotes y la elección se guarda por separado para cada workspace.

Escrito por el modelo de indexación a partir del texto del issue.