Add menu option to prune remote git branches

### Description

When working in projects, branches pile up, and so do remote branches.
Every now and then I have to carefully select the remote branches no longer on the server to remove the same origins in my local repo. Or I use one of the commands listed here: https://stackoverflow.com/questions/3184555/cleaning-up-old-remote-git-branches#3184742

- git branch -r -d origin/devel
- git remote prune origin
- git fetch origin --prune

### Use case/motivation

This allows to easier manage the git branches while the project proceeds.

### Related issues

_No response_

### Are you willing to submit a pull request?

No

No source file, test, or entry point is named. Start by locating NetBeans' Git branch-management UI and review how remote branches are currently handled. Use the listed git branch -r -d, git remote prune, and git fetch --prune commands as the requested behavior, then verify the new menu option performs the selected cleanup.

Written by the indexing model from the issue text.