[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_

ファイルもテストも指定されていないため、まず変更ビューまたはレビュー パネルと、そこに既にあるコミット済み/未コミットの変更のステータス表示を探します。アプリがコミットの push 済みかどうかをどのように判定しているかを追跡し、そのうえで、UI が push 済みの変更と単にコミット済みの変更を明確に区別していることを確認します。

索引モデルが issue の本文から書いたものです。