Autowire user provided `GitCredentialsProviderFactory`

Is your feature request related to a problem? Please describe.
Yes. I want to connect to github, but i need to use a github application to provide the authentication for the repos, reading the source code i couldn't figure out a way to plug in my custom github application implementation for a jgit credentialsprovider. (I've explained this a little bit here https://stackoverflow.com/questions/64715249/how-to-provide-custom-gitcredentialsproviderfactory-to-jgitenvironmentrepository)

Describe the solution you'd like
Be able to plug in a jgit CredentialsProvider in a clean way (Like setting up a bean, or injecting a bean and then adding my custom implementation, or something similar)

Describe alternatives you've considered
I think in the past the team has overriden classes from the framework and it kind of worked out, but it seems too hacky and a mess to maintain

Additional context

Start at GitCredentialsProviderFactory and the JGit CredentialsProvider integration described in the issue; inspect how Spring beans are currently created or injected. Confirm the intended extension point and define completion as allowing a user-provided provider to be wired cleanly without overriding framework classes. The issue names no source file or test, so repository-wide search and maintainer clarification are needed.