Git: use credentials helper

### Description

Netbeans should use git credentials saved by the credential helper.

### Use case/motivation

I would like Netbeans not to ask credentials when I perform an operation on a repo; it should use the configured credential helper like the git command line.
I have dozens of repos cloned from github and it's really painful updating the credentials every time an access token expires.

### Related issues

#4439 (not sure if really related)
JGit issue: https://bugs.eclipse.org/bugs/show_bug.cgi?id=441198
EGit issue: https://github.com/eclipse-egit/egit/issues/191

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

No

### Code of Conduct

Yes

Start by locating NetBeans' Git integration and reviewing the linked JGit issue 441198 and related EGit issue 191. The work is done when repository operations use the configured Git credential helper without repeatedly prompting for credentials.

Written by the indexing model from the issue text.