Add command to sync Git configuration with GitHub account

### Describe the feature or problem you’d like to solve

When setting up a new development environment, users need to manually configure Git with their GitHub account information. This is a simple task that could be automated.

### Proposed solution

Add a new `gh auth sync-gitconfig` command that automatically syncs Git configuration with the authenticated GitHub account information.

### Implementation

I have already implemented this feature and would like to contribute it.
Would the team be open to accepting this contribution? I can open a PR once this issue is approved.