Add ability to pin folders in the Project Explorer

## Description

I would like to request a feature that allows users to pin folders in the Project Explorer (the folder/file view on the left side of VS Code).

This would be especially helpful when working with large workspaces or monorepos, where the Project Explorer can contain many folders and navigating to frequently used folders can become time-consuming.

## Proposed functionality

Allow users to pin a folder in the Project Explorer so that the pinned folder remains easily accessible, regardless of its position in the workspace.

For example, a user could right-click a folder and select:
```
Pin Folder
```
Pinned folders could then be displayed in a dedicated Pinned section at the top of the Project Explorer.

## Use case

When working in a large workspace, developers often work repeatedly with a small number of folders that may be deeply nested or located far apart in the workspace.

Pinning these folders would make it much faster to access frequently used parts of the project without repeatedly scrolling or navigating through the folder hierarchy