Add a minimize/collapse action for long-running progress notifications

## Feature Request: Add a minimize/collapse action for long-running progress notifications

### Description

VS Code displays a persistent progress notification for long-running operations such as:

> Opening Java Projects: check details

When the operation takes a significant amount of time, this notification remains visible and cannot be dismissed or minimized while the operation continues.

This can obstruct part of the editor and become distracting, especially when working with large Java/Maven projects where project initialization or indexing may take several minutes.

### Expected behavior

Long-running progress notifications should provide an option to **minimize/collapse the notification** while allowing the underlying operation to continue.

For example:

* **Minimize/Collapse** → hides the notification from the editor area and moves the progress indication to the status bar.
* The user can later expand the notification to check its progress/details.
* The operation should continue normally in the background.

### Current behavior

The notification remains visible while the operation is running, with no obvious way to minimize it.

For example:

`Opening Java Projects: check details`

The notification can only disappear once the underlying operation finishes.

### Use case

This is particularly noticeable with the Java extension when opening large or multi-module Maven projects. Java project initialization can take several minutes, during which the progress notification remains on screen.

A similar minimize-to-status-bar behavior already exists for some long-running operations, so applying the same UX pattern to other persistent progress notifications would make the experience less intrusive.

### Suggested UI

Add a **Minimize/Collapse** button to persistent progress notifications.

When minimized:

`Opening Java Projects... [progress]`

could become a compact status-bar progress indicator or disappear into notification icon, while the user can continue using the editor without the notification taking up screen space.

### Screenshot

The attached screenshot shows the `Opening Java Projects: check details` notification remaining visible during Java project initialization.

### Environment

* VS Code: 1.134.0
* OS: Ubuntu/Linux
* Java project using Maven
* Java extension / Extension Pack for Java

### Related issue

This is related to the Java extension issue concerning the long-running `Opening Java Projects: check details` progress notification: #2643.

However, this request is specifically about **providing a way to minimize/collapse the progress notification**, rather than improving the Java project import performance.