Enable Mouse Keys while streaming for systems with no mouse plugged in

[cgutman]

Description

This PR introduces a workaround for the issue where Windows systems with no physical mouse connected would not display the mouse cursor (OS behavior since Windows 8). As a workaround, we can enable Mouse Keys for the duration of the streaming session which will force the mouse cursor to be displayed. Fortunately for us, Mouse Keys doesn't see input from SendInput() so we don't have to do anything special to make the number pad work either.

Screenshot

Issues Fixed or Closed

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

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[psyke83]

Tested with mouse driver disabled on Windows 10 - seems to be working perfectly.

Mouse Keys is enabled (if not already so) on stream start, making the cursor visible in this situation. Mouse Keys setting is also restored to the original setting before stream began.