✨ Display progress bar or loading indicator in Open Quickly

### Description

After opening a large monorepo, I thought the Open Quickly feature was broken because it took several seconds to perform a search, and there was no indication that a search was being performed in the background.

### Alternatives Considered

_No response_

### Additional Context

_No response_

### Screenshots

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先找出 CodeEdit macOS 應用程式中的 Open Quickly 搜尋流程，並追蹤背景搜尋是如何啟動的。在搜尋執行期間加入可見的進度或載入指示器，並確認它會在緩慢的搜尋期間顯示，且在結果準備好時停止。

由索引模型根據 Issue 內容生成。