Add Workspace flag to set an app/window as “Show on all virtual desktops”

### Description of the new feature / enhancement

Add an option in PowerToys Workspaces to automatically mark an app or window as visible on all virtual desktops when the workspace is launched.

### Scenario when this would be used?

Adding a “Show on all virtual desktops” flag to PowerToys Workspaces would significantly improve workflow consistency for users who rely on multiple virtual desktops. Some applications — such as browsers, note‑taking tools, communication apps, or monitoring dashboards — need to stay visible regardless of which desktop the user switches to.

Today this must be enabled manually for each window every time it opens, which breaks the repeatability that Workspaces is designed to provide.

By allowing Workspaces to automatically pin selected apps across all virtual desktops, users gain:

A predictable and fully reproducible workspace setup

Faster context switching without losing access to key tools

Better integration between Workspaces and Windows Virtual Desktops

Reduced manual steps and a smoother, more efficient workflow

This small addition would provide a large usability boost for power users who depend on structured, multi‑desktop environments.

### Supporting information

_No response_

Start in PowerToys Workspaces and trace how workspace app or window settings are stored and applied when a workspace launches. Read the existing Windows Virtual Desktops integration first; done means a selected app or window can be configured to show on all virtual desktops and that setting is applied during launch.

Written by the indexing model from the issue text.