Allow a configurable credential for github checks plugin instead of using the cred from the initial clone

### What feature do you want to see added?

I am looking for the ability to configure a specific credential for use with the github checks plugin. Right now, it appears to require a githup app credential in Jenkins. This is ok, but would be good to also be able to use a PAT where needed. I would also like to be able to use a different credential to clone the repo vs the credential used for the checks plugin.

Use Case: We have a github org where we cannot give global read access to the repo itself, but still want to enable github checks to work. Our org is managed in such a way and has too many repos for each repo to manage an app due to security constraints.

### Upstream changes

_No response_