[General] Provide more clarity on what changes have been pushed

### Feature summary

After making a change and raising a pull request and then making further changes it is hard to tell if the latest commits were pushed

### What problem are you trying to solve?

I made some changes with the agent then had it raise a PR to Azure DevOps, there was an issue with a UT and so I then requested additional changes in Github Copilot app. One time it made them, committed, and pushed, another time it committed but did not push.

### Proposed solution

Having a git viewer tab or in the changes view of the review panel it has the "committed" "uncommitted", having some indication of pushed would be really helpful.

### Workflow impact

Anyone updating an existing PR is impacted. Having to open terminal to look at git log or opening the pull request to double check that all the changes were pushed can lead to frustration.

### Installation context

_No response_

### Additional context

_No response_

No file or test is named; start by locating the changes view or review panel and its existing committed/uncommitted status display. Trace how the app determines whether commits have been pushed, then verify that the UI clearly distinguishes pushed from merely committed changes.

Written by the indexing model from the issue text.