On Issue, "checkout topic branch" should use existing branch if already created in UI

This is similar to #4120, but not identical.

There is a feature in the UI of the website, in the right side-bar of an issue, under "Development", to create a branch for an issue.

In VS Code PR and Issue view, under "Issues > Recent Issues", when clicking on an issue then the arrow to "Start working on issue and checkout topic branch", my feature requirements are :

• if a branch has already been created for this issue, use this branch instead of creating a new one
• if creating a new branch from here, give the user to rename this branch, and attach it to the issue so that it is visible in the issue side-bar on the github website, under the "Development" section

Commencez dans le flux Issues > Recent Issues de la vue PR and Issue de VS Code et suivez la commande derrière « Start working on issue and checkout topic branch. » Vérifiez comment l’association du branch Development de l’issue GitHub est représentée. Le travail est considéré comme terminé lorsqu’un branch existant de l’issue est réutilisé, tandis qu’un branch nouvellement créé peut être renommé et associé à l’issue pour être affiché dans GitHub.