【 Mouse Without Borders】Add support for creating virtual mouse and keyboard.

### Description of the new feature / enhancement

After starting **Mouse Without Borders**, a virtual mouse and a virtual keyboard will be automatically created in **Device Manager**.

### Scenario when this would be used?

This is to solve the following problem:
When a computer has no physical or other virtual keyboard/mouse devices at all, the operating system will provide a **software cursor**. This software cursor is unsuitable for normal system use:
First, its display priority is lower than that of some system UI layers, so the cursor will be hidden behind the UI.
Second, it is one to two times larger than a min mouse cursor and cannot be resized, making it very inconvenient to use.

**Concrete example**:
Computer A has a physical mouse; Computer B has no physical mouse.
After both are booted and Mouse Without Borders is running, you will find that the cursor on Computer B is the system-provided software mouse, with low display priority and a much larger size.

**Why add a virtual mouse and keyboard?**
I accidentally discovered that certain third-party software provides virtual mouse and keyboard devices. This allows Mouse Without Borders to maintain normal mouse functionality.
Without this, you would have to connect physical keyboards and mice to every computer.

### Supporting information

_No response_

Start by locating the Mouse Without Borders implementation and the Windows Device Manager integration points. Determine how virtual mouse and keyboard devices could be created and what operating-system behavior must be validated; done means both devices are automatically available and the remote cursor and keyboard work without physical devices.

Written by the indexing model from the issue text.